Impelement "Share to LOVE" support.

This allows you to share either .love game to launch as game (for the
non-fused APKs and instance of LOVE isn't running) or any file that
gets passed as love.filedropped.

Caveat: Ensure the intended game is running before sending files to LOVE app.
Otherwise, LOVE will attempt to open it as *.love file, which is may not what
you want.

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

@@ -0,0 +1,28 @@
+package org.love2d.android;
+
+import android.app.Activity;
+import android.content.Intent;
+import android.net.Uri;
+import android.os.Bundle;
+
+import androidx.annotation.Nullable;
+
+public class IntentReceiverActivity extends Activity {
+    @Override
+    protected void onCreate(@Nullable Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+
+        Intent mainIntent = getIntent();
+        Intent intent = new Intent(this, GameActivity.class);
+
+        if (mainIntent.getAction().equals(Intent.ACTION_SEND)) {
+            // Convert to simpler intent that our GameActivity can process.
+            Uri uri = mainIntent.getParcelableExtra(Intent.EXTRA_STREAM);
+            intent.setData(uri);
+            intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
+        }
+
+        startActivity(intent);
+        finish();
+    }
+}