Pausing should mute audio for looped music

Also adds pausing the surface in onPause and restoring it in onResume to avoid wasting resources when the activity is legitimately in the background.

app/src/main/java/emu/skyline/EmulationActivity.kt

@@ -346,13 +346,24 @@ class EmulationActivity : AppCompatActivity(), SurfaceHolder.Callback, View.OnTo
         executeApplication(intent!!)
     }
 
+    fun pauseEmulator() {
+        setSurface(null)
+        changeAudioStatus(false)
+    }
+
+    fun resumeEmulator() {
+        gameSurface?.let { setSurface(it) }
+        if (!emulationSettings.isAudioOutputDisabled)
+            changeAudioStatus(true)
+    }
+
     override fun onPause() {
         super.onPause()
 
         if (emulationSettings.forceMaxGpuClocks)
             GpuDriverHelper.forceMaxGpuClocks(false)
 
-        changeAudioStatus(false)
+        pauseEmulator()
     }
 
     override fun onStart() {
@@ -368,7 +379,7 @@ class EmulationActivity : AppCompatActivity(), SurfaceHolder.Callback, View.OnTo
     override fun onResume() {
         super.onResume()
 
-        changeAudioStatus(true)
+        resumeEmulator()
 
         if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.R) {
             @Suppress("DEPRECATION")
@@ -387,7 +398,7 @@ class EmulationActivity : AppCompatActivity(), SurfaceHolder.Callback, View.OnTo
             pictureInPictureReceiver = object : BroadcastReceiver() {
                 override fun onReceive(context : Context?, intent : Intent) {
                     if (intent.action == pauseIntentAction)
-                        setSurface(null)
+                        pauseEmulator()
                     else if (intent.action == muteIntentAction)
                         changeAudioStatus(false)
                 }
@@ -411,10 +422,7 @@ class EmulationActivity : AppCompatActivity(), SurfaceHolder.Callback, View.OnTo
                 // Perfectly acceptable and should be ignored
             }
 
-            gameSurface?.let { setSurface(it) }
-
-            if (!emulationSettings.isAudioOutputDisabled)
-                changeAudioStatus(true)
+            resumeEmulator()
             
             binding.onScreenControllerView.apply {
                 controllerType = inputHandler.getFirstControllerType()