Set Android applicationEntry to "Activity" during export.

Author: timbotimbo

example/unity/DemoApp/Assets/FlutterUnityIntegration/Editor/Build.cs

@@ -223,6 +223,9 @@ private static void DoBuildAndroid(String buildPath, bool isPlugin, bool isRelea
 #if UNITY_ANDROID && UNITY_6000_0_OR_NEWER
             UnityEditor.Android.UserBuildSettings.DebugSymbols.level = isReleaseBuild ? Unity.Android.Types.DebugSymbolLevel.None : Unity.Android.Types.DebugSymbolLevel.SymbolTable;
             UnityEditor.Android.UserBuildSettings.DebugSymbols.format = Unity.Android.Types.DebugSymbolFormat.LegacyExtensions;
+#endif
+#if UNITY_ANDROID && UNITY_2023_1_OR_NEWER
+            PlayerSettings.Android.applicationEntry = AndroidApplicationEntry.Activity;
 #endif
             // Switch to Android standalone build.
             EditorUserBuildSettings.SwitchActiveBuildTarget(BuildTargetGroup.Android, BuildTarget.Android);