fix(ivy): properly rewrite imports in generated factory shims (#27998)

Generated factory shims can import from @angular/core. However, we have
special logic in place to rewrite self-imports when generating code for
@angular/core.

This commit leverages the new standalone ImportRewriter interface to
properly rewrite imports in generated factory shims. Before this fix,
a generated factory file for core would look like:

```typescript
import * as i0 from './r3_symbols';

export var ApplicationModuleNgFactory = new ɵNgModuleFactory(...);
```

This is invalid, as ɵNgModuleFactory is just NgModuleFactory when imported
via r3_symbols.

FW-881 #resolve

PR Close #27998

packages/compiler-cli/test/ngtsc/ngtsc_spec.ts

@@ -905,6 +905,29 @@ describe('ngtsc behavioral tests', () => {
     expect(emptyFactory).toContain(`export var ɵNonEmptyModule = true;`);
   });
 
+  it('should generate correct imports in factory stubs when compiling @angular/core', () => {
+    env.tsconfig({'allowEmptyCodegenFiles': true});
+
+    env.write('test.ts', `
+        import {NgModule} from '@angular/core';
+
+        @NgModule({})
+        export class TestModule {}
+    `);
+
+    // Trick the compiler into thinking it's compiling @angular/core.
+    env.write('r3_symbols.ts', 'export const ITS_JUST_ANGULAR = true;');
+
+    env.driveMain();
+
+    const factoryContents = env.getContents('test.ngfactory.js');
+    expect(normalize(factoryContents)).toBe(normalize(`
+      import * as i0 from "./r3_symbols";
+      import { TestModule } from './test';
+      export var TestModuleNgFactory = new i0.NgModuleFactory(TestModule);
+    `));
+  });
+
   it('should generate a summary stub for decorated classes in the input file only', () => {
     env.tsconfig({'allowEmptyCodegenFiles': true});
 
@@ -1635,3 +1658,7 @@ function expectTokenAtPosition<T extends ts.Node>(
   expect(guard(node)).toBe(true);
   return node as T;
 }
+
+function normalize(input: string): string {
+  return input.replace(/\s+/g, ' ').trim();
+}