feat(ivy): @NgModule -> ngInjectorDef compilation (#22458)

This adds compilation of @NgModule providers and imports into
ngInjectorDef statements in generated code. All @NgModule annotations
will be compiled and the @NgModule decorators removed from the
resultant js output.

All @Injectables will also be compiled in Ivy mode, and the decorator
removed.

PR Close #22458

packages/core/src/di/injection_token.ts

@@ -8,7 +8,7 @@
 
 import {Type} from '../type';
 
-import {InjectableDef, defineInjectable} from './injectable';
+import {InjectableDef, defineInjectable} from './defs';
 
 /**
  * Creates a token that can be used in a DI Provider.
@@ -26,8 +26,24 @@ import {InjectableDef, defineInjectable} from './injectable';
  * // myInterface is inferred to be MyInterface.
  * ```
  *
+ * When creating an `InjectionToken`, you can optionally specify a factory function which returns
+ * (possibly by creating) a default value of the parameterized type `T`. This sets up the
+ * `InjectionToken` using this factory as a provider as if it was defined explicitly in the
+ * application's root injector. If the factory function, which takes zero arguments, needs to inject
+ * dependencies, it can do so using the `inject` function. See below for an example.
+ *
+ * Additionally, if a `factory` is specified you can also specify the `providedIn` option, which
+ * overrides the above behavior and marks the token as belonging to a particular `@NgModule`. As
+ * mentioned above, `'root'` is the default value for `providedIn`.
+ *
  * ### Example
  *
+ * #### Tree-shakeable InjectionToken
+ *
+ * {@example core/di/ts/injector_spec.ts region='ShakeableInjectionToken'}
+ *
+ * #### Plain InjectionToken
+ *
  * {@example core/di/ts/injector_spec.ts region='InjectionToken'}
  *
  * @stable
@@ -54,3 +70,7 @@ export class InjectionToken<T> {
 
   toString(): string { return `InjectionToken ${this._desc}`; }
 }
+
+export interface InjectableDefToken<T> extends InjectionToken<T> {
+  ngInjectableDef: InjectableDef<T>;
+}