refactor: optimize plugins for angular treeshaking

BREAKING CHANGE: You can remove the plugin import from the app.module.ts because of the changed Inject decorator

src/@ionic-native/plugins/photo-library/index.ts

@@ -115,7 +115,9 @@ export function CordovaFiniteObservable(
   installVariables: ['PHOTO_LIBRARY_USAGE_DESCRIPTION'],
   platforms: ['Android', 'Browser', 'iOS']
 })
-@Injectable()
+@Injectable({
+  providedIn: 'root'
+})
 export class PhotoLibrary extends IonicNativePlugin {
   /**
    * Retrieves library items. Library item contains photo metadata like width and height, as well as photoURL and thumbnailURL.