fix(core): avoid false-positive deprecation when using InjectionToken with factory only

Prevents the deprecation warning that was incorrectly triggered when
defining an InjectionToken with only a `factory`, which correctly
defaults to the `root` scope.

packages/core/src/di/injection_token.ts

@@ -74,7 +74,7 @@ export class InjectionToken<T> {
   constructor(
     _desc: string,
     options: {
-      providedIn?: Type<any> | 'any';
+      providedIn: Type<any> | 'any';
       factory: () => T;
     },
   );