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/audio-management/index.ts

@@ -47,7 +47,9 @@ import { Cordova, IonicNativePlugin, Plugin } from '@ionic-native/core';
   repo: 'https://github.com/clovelCed/cordova-plugin-audiomanagement',
   platforms: ['Android']
 })
-@Injectable()
+@Injectable({
+  providedIn: 'root'
+})
 export class AudioManagement extends IonicNativePlugin {
   /**
    * Sets the `AudioManagement.AudioMode` for the device.