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/base64/index.ts

@@ -31,7 +31,9 @@ import { Cordova, IonicNativePlugin, Plugin } from '@ionic-native/core';
   repo: 'https://github.com/hazemhagrass/phonegap-base64',
   platforms: ['Android', 'iOS']
 })
-@Injectable()
+@Injectable({
+  providedIn: 'root'
+})
 export class Base64 extends IonicNativePlugin {
 
   /**