Android: Use SwipeRefreshLayout in MainActivity

The main reason why I'm adding this isn't actually to allow
users to swipe down to refresh, it's to add a loading indicator.
Considering that the Storage Access Framework can be slow for
folders with many items (many subfolders?), not showing a
loading indicator might give users the impression that adding
a folder resulted in nothing happening even though Dolphin is
scanning for games in the background. But I suppose letting
users swipe down to refresh is a nice bonus with the change.

Source/Android/app/src/main/res/layout/activity_tv_main.xml

@@ -1,7 +1,20 @@
 <?xml version="1.0" encoding="utf-8"?>
-<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
-             android:id="@+id/content"
-             android:layout_width="match_parent"
-             android:layout_height="match_parent">
 
-</FrameLayout>
+<!-- The SwipeRefreshLayout is used mainly for its ability to show a loading indicator, not for
+     its ability to detect swipes. But if someone is using this activity with a touchscreen
+     for whatever reason, we get the ability to refresh by swiping down more or less for free. -->
+
+<androidx.swiperefreshlayout.widget.SwipeRefreshLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:id="@+id/swipe_refresh"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent">
+
+    <FrameLayout
+         android:id="@+id/content"
+         android:layout_width="match_parent"
+         android:layout_height="match_parent">
+
+    </FrameLayout>
+
+</androidx.swiperefreshlayout.widget.SwipeRefreshLayout>

Source/Android/app/src/main/res/layout/fragment_grid.xml

@@ -4,12 +4,19 @@
              android:layout_width="match_parent"
              android:layout_height="match_parent">
 
-    <androidx.recyclerview.widget.RecyclerView
-        android:id="@+id/grid_games"
+    <androidx.swiperefreshlayout.widget.SwipeRefreshLayout
+        android:id="@+id/swipe_refresh"
         android:layout_width="match_parent"
         android:layout_height="match_parent"
         android:layout_marginLeft="@dimen/activity_horizontal_margin"
-        android:layout_marginRight="@dimen/activity_horizontal_margin"
-        tools:listitem="@layout/card_game"/>
+        android:layout_marginRight="@dimen/activity_horizontal_margin">
+
+        <androidx.recyclerview.widget.RecyclerView
+            android:id="@+id/grid_games"
+            android:layout_width="match_parent"
+            android:layout_height="match_parent"
+            tools:listitem="@layout/card_game"/>
+
+    </androidx.swiperefreshlayout.widget.SwipeRefreshLayout>
 
 </FrameLayout>