Moving manifest `manifest.application$name` attribute to the main manifest, to make it available for both fdroid and gplay variant. Fixes #6995.

vector-app/src/gplay/AndroidManifest.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android">
 
-    <application android:name="im.vector.app.VectorApplication">
+    <application>
 
         <!-- Firebase components -->
         <meta-data

vector-app/src/main/AndroidManifest.xml

@@ -4,6 +4,7 @@
     package="im.vector.application">
 
     <application
+        android:name="im.vector.app.VectorApplication"
         android:allowBackup="false"
         android:hasFragileUserData="true"
         android:icon="@mipmap/ic_launcher"