fix: cut down memory usage in ApiVersionsRegistry

This commit adds the following improvements to the ApiVersionsRegistry implementation :

- Use Java StAX parser for memory-efficient XML processing
- Reduce object allocations for representing API version info by reusing ApiVersion instances which represent the same API versions.
- Trim method return types in method signature strings to reduce memory usage by a small amount
- A single model class is now used to represent the API information. Earlier, we had different classes to represent API info for classes, fields and metnods.

Author: itsaky

core/app/src/main/java/com/itsaky/androidide/actions/file/SaveFileAction.kt

@@ -22,7 +22,7 @@ import androidx.core.content.ContextCompat
 import com.itsaky.androidide.actions.ActionData
 import com.itsaky.androidide.actions.EditorRelatedAction
 import com.itsaky.androidide.models.SaveResult
-import com.itsaky.androidide.projects.ProjectManagerImpl
+import com.itsaky.androidide.projects.internal.ProjectManagerImpl
 import com.itsaky.androidide.resources.R
 import com.itsaky.androidide.utils.flashError
 import com.itsaky.androidide.utils.flashSuccess

core/app/src/main/java/com/itsaky/androidide/activities/MainActivity.kt

@@ -32,7 +32,7 @@ import com.itsaky.androidide.activities.editor.EditorActivityKt
 import com.itsaky.androidide.app.EdgeToEdgeIDEActivity
 import com.itsaky.androidide.databinding.ActivityMainBinding
 import com.itsaky.androidide.preferences.internal.GeneralPreferences
-import com.itsaky.androidide.projects.ProjectManagerImpl
+import com.itsaky.androidide.projects.internal.ProjectManagerImpl
 import com.itsaky.androidide.resources.R.string
 import com.itsaky.androidide.templates.ITemplateProvider
 import com.itsaky.androidide.utils.DialogUtils

core/app/src/main/java/com/itsaky/androidide/activities/editor/BaseEditorActivity.kt

@@ -84,7 +84,7 @@ import com.itsaky.androidide.models.Range
 import com.itsaky.androidide.models.SearchResult
 import com.itsaky.androidide.preferences.internal.BuildPreferences
 import com.itsaky.androidide.projects.IProjectManager
-import com.itsaky.androidide.projects.ProjectManagerImpl
+import com.itsaky.androidide.projects.internal.ProjectManagerImpl
 import com.itsaky.androidide.tasks.cancelIfActive
 import com.itsaky.androidide.ui.CodeEditorView
 import com.itsaky.androidide.ui.ContentTranslatingDrawerLayout

core/app/src/main/java/com/itsaky/androidide/activities/editor/EditorHandlerActivity.kt

@@ -51,7 +51,7 @@ import com.itsaky.androidide.models.OpenedFile
 import com.itsaky.androidide.models.OpenedFilesCache
 import com.itsaky.androidide.models.Range
 import com.itsaky.androidide.models.SaveResult
-import com.itsaky.androidide.projects.ProjectManagerImpl
+import com.itsaky.androidide.projects.internal.ProjectManagerImpl
 import com.itsaky.androidide.tasks.executeAsync
 import com.itsaky.androidide.ui.CodeEditorView
 import com.itsaky.androidide.utils.DialogUtils.newYesNoDialog

core/app/src/main/java/com/itsaky/androidide/activities/editor/ProjectHandlerActivity.kt

@@ -39,7 +39,7 @@ import com.itsaky.androidide.lookup.Lookup
 import com.itsaky.androidide.lsp.IDELanguageClientImpl
 import com.itsaky.androidide.lsp.java.utils.CancelChecker
 import com.itsaky.androidide.preferences.internal.GeneralPreferences
-import com.itsaky.androidide.projects.ProjectManagerImpl
+import com.itsaky.androidide.projects.internal.ProjectManagerImpl
 import com.itsaky.androidide.projects.api.GradleProject
 import com.itsaky.androidide.projects.builder.BuildService
 import com.itsaky.androidide.services.builder.GradleBuildService

core/app/src/main/java/com/itsaky/androidide/handlers/EditorActivityLifecyclerObserver.kt

@@ -28,7 +28,7 @@ import com.itsaky.androidide.eventbus.events.editor.OnPauseEvent
 import com.itsaky.androidide.eventbus.events.editor.OnResumeEvent
 import com.itsaky.androidide.eventbus.events.editor.OnStartEvent
 import com.itsaky.androidide.eventbus.events.editor.OnStopEvent
-import com.itsaky.androidide.projects.ProjectManagerImpl
+import com.itsaky.androidide.projects.internal.ProjectManagerImpl
 import com.itsaky.androidide.projects.util.BootClasspathProvider
 import com.itsaky.androidide.utils.EditorActivityActions
 import com.itsaky.androidide.utils.EditorSidebarActions

core/app/src/main/java/com/itsaky/androidide/services/builder/GradleBuildService.kt

@@ -34,7 +34,7 @@ import com.itsaky.androidide.lookup.Lookup
 import com.itsaky.androidide.managers.ToolsManager
 import com.itsaky.androidide.preferences.internal.BuildPreferences
 import com.itsaky.androidide.preferences.internal.DevOpsPreferences
-import com.itsaky.androidide.projects.ProjectManagerImpl
+import com.itsaky.androidide.projects.internal.ProjectManagerImpl
 import com.itsaky.androidide.projects.builder.BuildService
 import com.itsaky.androidide.resources.R
 import com.itsaky.androidide.services.ToolingServerNotStartedException

core/indexing-core/src/main/java/com/itsaky/androidide/indexing/core/platform/ApiVersion.kt

@@ -23,30 +23,33 @@ interface ICompletionData
 /**
  * Information about a class-related completion item.
  *
- * @property className The fully qualified name of the class.
+ * @property className The fully qualified name of the class. Example: `pck.outer.inner`.
+ * @property flatName The flat name of the class. Example: `pck.outer$inner`.
+ * @property isCompleteData Whether the data provided by this [ClassCompletionData] is complete.
  * @property isNested Whether the given class is a nested class or not.
  * @property topLevelClass If [isNested] is true, then this must be set to the fully qualified name
+ * of the top-level class.
  * @property simpleName The simple name of the class.
  * @property nameWithoutTopLevel The name of this class without the fully qualified name of its top
  * level class. For example, the value of this property for class name
  * `com.my.pck.MyClass.Inner.InnerInner` will be `Inner.InnerInner`
  */
 data class ClassCompletionData
 @JvmOverloads
-constructor(val className: String, val isNested: Boolean = false, val topLevelClass: String = "") :
-  ICompletionData {
-  val simpleName: String
-    get() {
-      return className.substringAfterLast(delimiter = '.')
-    }
+constructor(
+  val className: String,
+  val isCompleteData: Boolean = false,
+  val flatName: String = className,
+  val simpleName: String = className.substringAfterLast(delimiter = '.'),
+  val isNested: Boolean = false,
+  val topLevelClass: String = ""
+) : ICompletionData {
 
-  val nameWithoutTopLevel: String
-    get() {
-      if (!isNested) {
-        return className
-      }
-      return className.substring(topLevelClass.length + 1)
-    }
+  val nameWithoutTopLevel: String = if (isNested) {
+    className.substring(topLevelClass.length + 1)
+  } else {
+    className
+  }
 }
 
 /**

core/lsp-models/src/main/java/com/itsaky/androidide/lsp/models/CompletionData.kt

@@ -15,7 +15,7 @@
  *   along with AndroidIDE.  If not, see <https://www.gnu.org/licenses/>.
  */
 
-package com.itsaky.androidide.projects
+package com.itsaky.androidide.projects.internal
 
 import androidx.annotation.RestrictTo
 import com.android.builder.model.v2.models.ProjectSyncIssues
@@ -29,6 +29,9 @@ import com.itsaky.androidide.eventbus.events.file.FileEvent
 import com.itsaky.androidide.eventbus.events.file.FileRenameEvent
 import com.itsaky.androidide.eventbus.events.project.ProjectInitializedEvent
 import com.itsaky.androidide.lookup.Lookup
+import com.itsaky.androidide.projects.CachingProject
+import com.itsaky.androidide.projects.IProjectManager
+import com.itsaky.androidide.projects.R
 import com.itsaky.androidide.projects.api.AndroidModule
 import com.itsaky.androidide.projects.api.ModuleProject
 import com.itsaky.androidide.projects.api.Project