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-cli/integrationtest/bazel/injectable_def/lib1/module.ts

@@ -13,7 +13,7 @@ export class Lib1Module {
 }
 
 @Injectable({
-  scope: Lib1Module,
+  providedIn: Lib1Module,
 })
 export class Service {
   static instanceCount = 0;