feat(plugin): add MS App Center LowMemory plugin (#3619)

* feat(plugin): add MS App Center LowMemory plugin

* refactor(app-center-low-memory): plugin decorator

src/@ionic-native/plugins/app-center-low-memory/index.ts

@@ -0,0 +1,41 @@
+import { Injectable } from '@angular/core';
+import { Cordova, IonicNativePlugin, Plugin } from '@ionic-native/core';
+
+/**
+ * @name App Center Low Memory
+ * @description
+ * Generates a low memory warning.
+ * For more info, please see: https://github.com/Microsoft/appcenter-sdk-cordova/tree/master/cordova-plugin-appcenter-generate-low-memory
+ * 
+ * @usage
+ * ```typescript
+ * import { LowMemory } from '@ionic-native/app-center-low-memory/ngx';
+ * 
+ * ...
+ *
+ * constructor(private lowMemory: LowMemory) { }
+ *
+ * async warning() {    
+ *   await this.lowMemory.generateLowMemory();
+ * }
+ * ```
+ */
+@Plugin({
+  pluginName: 'LowMemory',
+  plugin: 'https://github.com/Microsoft/appcenter-sdk-cordova/tree/master/cordova-plugin-appcenter-generate-low-memory',
+  pluginRef: 'LowMemory',
+  repo: 'https://github.com/Microsoft/appcenter-sdk-cordova/tree/master/cordova-plugin-appcenter-generate-low-memory',
+  platforms: ['Android', 'iOS'],
+})
+@Injectable()
+export class LowMemory extends IonicNativePlugin {
+  /**
+   * Generates a low memory warning.
+   * For more info, please see: https://github.com/Microsoft/appcenter-sdk-cordova/tree/master/cordova-plugin-appcenter-generate-low-memory
+   * @returns {Promise<void>}
+   */
+  @Cordova()
+  generateLowMemory(): Promise<void> {
+    return;
+  }
+}