refactor(ivy): generate ngFactoryDef for injectables (#32433)

With #31953 we moved the factories for components, directives and pipes into a new field called `ngFactoryDef`, however I decided not to do it for injectables, because they needed some extra logic. These changes set up the `ngFactoryDef` for injectables as well.

For reference, the extra logic mentioned above is that for injectables we have two code paths:

1. For injectables that don't configure how they should be instantiated, we create a `factory` that proxies to `ngFactoryDef`:

```
// Source
@Injectable()
class Service {}

// Output
class Service {
  static ngInjectableDef = defineInjectable({
    factory: () => Service.ngFactoryFn(),
  });

  static ngFactoryFn: (t) => new (t || Service)();
}
```

2. For injectables that do configure how they're created, we keep the `ngFactoryDef` and generate the factory based on the metadata:

```
// Source
@Injectable({
  useValue: DEFAULT_IMPL,
})
class Service {}

// Output
export class Service {
  static ngInjectableDef = defineInjectable({
    factory: () => DEFAULT_IMPL,
  });

  static ngFactoryFn: (t) => new (t || Service)();
}
```

PR Close #32433

packages/core/src/r3_symbols.ts

@@ -25,6 +25,7 @@ export {ɵɵinject} from './di/injector_compatibility';
 export {ɵɵInjectableDef, ɵɵInjectorDef, ɵɵdefineInjectable, ɵɵdefineInjector} from './di/interface/defs';
 export {NgModuleDef, ɵɵNgModuleDefWithMeta} from './metadata/ng_module';
 export {ɵɵdefineNgModule} from './render3/definition';
+export {ɵɵFactoryDef} from './render3/interfaces/definition';
 export {setClassMetadata} from './render3/metadata';
 export {NgModuleFactory} from './render3/ng_module_ref';