Revert "Revert "fix: proprietory classes included into build""

This reverts commit fa1d9fd72f2bf0beb2826ca42acf0bd342fec7a2.

android/app/src/main/kotlin/chat/fluffy/fluffychat/MainActivity.kt

@@ -7,11 +7,13 @@ import android.content.Context
 import androidx.multidex.MultiDex
 
 class MainActivity : FlutterActivity() {
+
     override fun attachBaseContext(base: Context) {
         super.attachBaseContext(base)
         MultiDex.install(this)
     }
 
+
     override fun provideFlutterEngine(context: Context): FlutterEngine? {
         return provideEngine(this)
     }