Fix landscape view induced MainActivity leak.

With landscape view enabled (e.g. e06b2c7) in the app and auto
rotation enabled on the phone, switching between portrait and
landscape orientations leaks instances of MainActivity.  This prevents
garbage collection of not just the MainActivity object, but fragments
and other objects referenced by the Activity.

This is caused by repositories, the AppContext instance, the player
service, and authentication code maintaining a reference to the
context which with they are initialized.  So rather than initialize
these with an Activity context, pass them the Application context.

Activities are torn down and rebuilt on screen rotation.  The
Application context is not.

To enable instantiation of the FavoritedRepository with the
Application context, delay that repository’s initialization until
first use.  This ensures the Application context is fully initialized.
It is not fully initialized until the MainActivity has been fully
initialized.

app/src/main/java/audio/funkwhale/ffa/activities/MainActivity.kt

@@ -69,7 +69,9 @@ class MainActivity : AppCompatActivity() {
     LOGOUT(1001)
   }
 
-  private val favoritedRepository = FavoritedRepository(this)
+  private val favoritedRepository by lazy {
+    FavoritedRepository(applicationContext)
+  }
   private var menu: Menu? = null
 
   private lateinit var binding: ActivityMainBinding
@@ -82,8 +84,7 @@ class MainActivity : AppCompatActivity() {
 
   override fun onCreate(savedInstanceState: Bundle?) {
     super.onCreate(savedInstanceState)
-    AppContext.init(this)
-
+    AppContext.init(applicationContext)
     binding = ActivityMainBinding.inflate(layoutInflater)
 
     (supportFragmentManager.findFragmentById(R.id.now_playing) as NowPlayingFragment).apply {
@@ -141,15 +142,15 @@ class MainActivity : AppCompatActivity() {
     super.onResume()
 
     binding.nowPlaying.getFragment<NowPlayingFragment>().apply {
-      favoritedRepository.update(this@MainActivity, lifecycleScope)
+      favoritedRepository.update(applicationContext, lifecycleScope)
 
-      startService(Intent(this@MainActivity, PlayerService::class.java))
-      DownloadService.start(this@MainActivity, PinService::class.java)
+      startService(Intent(applicationContext, PlayerService::class.java))
+      DownloadService.start(applicationContext, PinService::class.java)
 
       CommandBus.send(Command.RefreshService)
 
       lifecycleScope.launch(IO) {
-        Userinfo.get(this@MainActivity, oAuth)
+        Userinfo.get(applicationContext, oAuth)
       }
     }
   }
@@ -343,7 +344,7 @@ class MainActivity : AppCompatActivity() {
         try {
           Fuel
             .post(mustNormalizeUrl("/api/v1/history/listenings/"))
-            .authorize(this@MainActivity, oAuth)
+            .authorize(applicationContext, oAuth)
             .header("Content-Type", "application/json")
             .body(Gson().toJson(mapOf("track" to track.id)))
             .awaitStringResponse()

app/src/main/java/audio/funkwhale/ffa/utils/AppContext.kt

@@ -1,7 +1,6 @@
 package audio.funkwhale.ffa.utils
 
 import android.annotation.SuppressLint
-import android.app.Activity
 import android.app.NotificationChannel
 import android.app.NotificationManager
 import android.content.BroadcastReceiver
@@ -23,7 +22,7 @@ object AppContext {
   const val PAGE_SIZE = 50
   const val TRANSITION_DURATION = 300L
 
-  fun init(context: Activity) {
+  fun init(context: Context) {
     setupNotificationChannels(context)
 
     // CastContext.getSharedInstance(context)