fix(language-service): Diagnostic span should point to class name (#34932)

Right now, if an Angular diagnostic is generated for a TypeScript node,
the span points to the decorator Identifier, i.e. the Identifier node
like `@NgModule`, `@Component`, etc.
This is weird. It should point to the class name instead.
Note, we do not have a more fine-grained breakdown of the span when
diagnostics are emitted, this work remains to be done.

PR Close #34932

packages/language-service/test/utils_spec.ts

@@ -28,10 +28,10 @@ describe('getDirectiveClassLike()', () => {
       }
     });
     expect(result).toBeTruthy();
-    const {decoratorId, classDecl} = result !;
+    const {decoratorId, classId} = result !;
     expect(decoratorId.kind).toBe(ts.SyntaxKind.Identifier);
-    expect((decoratorId as ts.Identifier).text).toBe('NgModule');
-    expect(classDecl.name !.text).toBe('AppModule');
+    expect(decoratorId.text).toBe('NgModule');
+    expect(classId.text).toBe('AppModule');
   });
 });