Move emulation lifecycle handling into EmulationFragment.

The Activity is responsible for just its views and menus and such. It
signals the Fragment via setGamePath, StartEmulation and StopEmulation.

The Fragment manages the actual emulation lifecycle. It is solely
responsible for calling the NativeLibrary lifecycle methods.

With this lifecycle simplification, the NativeLibrary no longer needs to
kill the Activity. It happens normally now.

This simplifies a lot of things, live handling rotation.

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

@@ -3,11 +3,11 @@
              android:layout_height="match_parent"
              android:id="@+id/frame_content">
 
-    <FrameLayout
-        android:id="@+id/frame_emulation_fragment"
+    <fragment
+        android:id="@+id/fragment_emulation"
+        android:name="org.dolphinemu.dolphinemu.fragments.EmulationFragment"
         android:layout_width="match_parent"
-        android:layout_height="match_parent"
-        android:visibility="invisible"/>
+        android:layout_height="match_parent"/>
 
     <ImageView
         android:layout_width="match_parent"