Initial 12.0 refactor.

There are no guarantees this commit will compile.

app/src/main/java/org/love2d/android/GameActivity.java

@@ -0,0 +1,14 @@
+package org.love2d.android;
+
+import androidx.appcompat.app.AppCompatActivity;
+import org.libsdl.app.SDLActivity;
+
+import android.os.Bundle;
+
+public class GameActivity extends SDLActivity {
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+    }
+}