refactor: deprecate universalProject in app-shell schematics as it's unused

Author: alan-agius4

packages/schematics/angular/app-shell/index_spec.ts

@@ -19,7 +19,6 @@ describe('App Shell Schematic', () => {
   const defaultOptions: AppShellOptions = {
     name: 'foo',
     clientProject: 'bar',
-    universalProject: 'universal',
   };
 
   const workspaceOptions: WorkspaceOptions = {

packages/schematics/angular/app-shell/schema.json

@@ -12,7 +12,8 @@
     },
     "universalProject": {
       "type": "string",
-      "description": "The name of related Universal app."
+      "description": "The name of related Universal app.",
+      "x-deprecated": "This option has no effect."
     },
     "route": {
       "type": "string",
@@ -98,7 +99,6 @@
     }
   },
   "required": [
-    "clientProject",
-    "universalProject"
+    "clientProject"
   ]
 }