fix(ivy): NgOnChangesFeature no longer included in hello_world (#28187)

- Wraps the NgOnChangesFeature in a factory such that no side effects occur in the module root
- Adds comments to ngInherit property on feature definition interface to help guide others not to make the same mistake
- Updates compiler to generate the feature properly after the change to it being a factory
- Updates appropriate tests

PR Close #28187

packages/core/src/render3/features/ng_onchanges_feature.ts

@@ -35,11 +35,18 @@ type OnChangesExpando = OnChanges & {
  * static ngComponentDef = defineComponent({
  *   ...
  *   inputs: {name: 'publicName'},
- *   features: [NgOnChangesFeature]
+ *   features: [NgOnChangesFeature()]
  * });
  * ```
  */
-export function NgOnChangesFeature<T>(definition: DirectiveDef<T>): void {
+export function NgOnChangesFeature<T>(): DirectiveDefFeature {
+  // This option ensures that the ngOnChanges lifecycle hook will be inherited
+  // from superclasses (in InheritDefinitionFeature).
+  (NgOnChangesFeatureImpl as DirectiveDefFeature).ngInherit = true;
+  return NgOnChangesFeatureImpl;
+}
+
+function NgOnChangesFeatureImpl<T>(definition: DirectiveDef<T>): void {
   if (definition.type.prototype.ngOnChanges) {
     definition.setInput = ngOnChangesSetInput;
 
@@ -91,11 +98,6 @@ function setSimpleChangesStore(instance: any, store: NgSimpleChangesStore): NgSi
   return instance[SIMPLE_CHANGES_STORE] = store;
 }
 
-// This option ensures that the ngOnChanges lifecycle hook will be inherited
-// from superclasses (in InheritDefinitionFeature).
-(NgOnChangesFeature as DirectiveDefFeature).ngInherit = true;
-
-
 interface NgSimpleChangesStore {
   previous: SimpleChanges;
   current: SimpleChanges|null;

packages/core/src/render3/interfaces/definition.ts

@@ -302,11 +302,27 @@ export type PipeDefWithMeta<T, Name extends string> = PipeDef<T>;
 
 export interface DirectiveDefFeature {
   <T>(directiveDef: DirectiveDef<T>): void;
+  /**
+   * Marks a feature as something that {@link InheritDefinitionFeature} will execute
+   * during inheritance.
+   *
+   * NOTE: DO NOT SET IN ROOT OF MODULE! Doing so will result in tree-shakers/bundlers
+   * identifying the change as a side effect, and the feature will be included in
+   * every bundle.
+   */
   ngInherit?: true;
 }
 
 export interface ComponentDefFeature {
   <T>(componentDef: ComponentDef<T>): void;
+  /**
+   * Marks a feature as something that {@link InheritDefinitionFeature} will execute
+   * during inheritance.
+   *
+   * NOTE: DO NOT SET IN ROOT OF MODULE! Doing so will result in tree-shakers/bundlers
+   * identifying the change as a side effect, and the feature will be included in
+   * every bundle.
+   */
   ngInherit?: true;
 }