feat: tree-shakeable providers API updates (#22655)

Rename @Injectable({scope -> providedIn}).

Instead of {providedIn: APP_ROOT_SCOPE}, accept {providedIn: 'root'}.
Also, {providedIn: null} implies the injectable should not be added
to any scope.

PR Close #22655

packages/compiler/src/metadata_resolver.ts

@@ -801,7 +801,7 @@ export class CompileMetadataResolver {
     return {
       symbol: type,
       type: typeMetadata,
-      module: meta.scope || undefined,
+      providedIn: meta.providedIn,
       useValue: meta.useValue,
       useClass: meta.useClass,
       useExisting: meta.useExisting,