include all resources in a build target's sources list

Author: matthewbastien

Sources/BuildSystemIntegration/SwiftPMBuildSystem.swift

@@ -565,6 +565,27 @@ package actor SwiftPMBuildSystem: BuiltInBuildSystem {
           data: SourceKitSourceItemData(isHeader: true).encodeToLSPAny()
         )
       }
+      sources += swiftPMTarget.resources.map {
+        SourceItem(
+          uri: DocumentURI($0),
+          kind: $0.isDirectory ? .directory : .file,
+          generated: false,
+        )
+      }
+      sources += swiftPMTarget.ignored.map {
+        SourceItem(
+          uri: DocumentURI($0),
+          kind: $0.isDirectory ? .directory : .file,
+          generated: false,
+        )
+      }
+      sources += swiftPMTarget.others.map {
+        SourceItem(
+          uri: DocumentURI($0),
+          kind: $0.isDirectory ? .directory : .file,
+          generated: false,
+        )
+      }
       result.append(SourcesItem(target: target, sources: sources))
     }
     return BuildTargetSourcesResponse(items: result)
@@ -760,3 +781,9 @@ package actor SwiftPMBuildSystem: BuiltInBuildSystem {
     return TextDocumentSourceKitOptionsResponse(compilerArguments: compilerArgs)
   }
 }
+
+fileprivate extension URL {
+  var isDirectory: Bool {
+    (try? resourceValues(forKeys: [.isDirectoryKey]))?.isDirectory == true
+  }
+}