fix: support an Application instance in PackageList for Android (#493)

Author: Salakar

packages/platform-android/native_modules.gradle

@@ -17,10 +17,16 @@ import java.util.ArrayList;
 {{ packageImports }}
 
 public class PackageList {
+  private Application application;
   private ReactNativeHost reactNativeHost;
   public PackageList(ReactNativeHost reactNativeHost) {
     this.reactNativeHost = reactNativeHost;
   }
+  
+  public PackageList(Application application) {
+    this.reactNativeHost = null;
+    this.application = application;
+  }
 
   private ReactNativeHost getReactNativeHost() {
     return this.reactNativeHost;
@@ -31,6 +37,7 @@ public class PackageList {
   }
 
   private Application getApplication() {
+    if (this.reactNativeHost == null) return this.application;
     return this.reactNativeHost.getApplication();
   }