Added Direct Play and websocket improvements

* [backend]: Websocket now automatically tries to reconnect if connection was lost, up to 3 times.
* [backend]: Move more playback and resume logic to the backend, to avoid having it in multiple places within the QML. Regression: pausing playback sometimes halts the video player for an unknown reason.
* [playback]: Sailfin will try to play without the server transcoding, if possible.
* [ui]: added a debug page in the settings

sailfish/qml/harbour-sailfin.qml

@@ -33,12 +33,16 @@ ApplicationWindow {
     property bool _hasInitialized: false
     // The global mediaPlayer instance
     readonly property MediaPlayer mediaPlayer: _mediaPlayer
+    readonly property PlaybackManager playbackManager: _playbackManager
 
     // Data of the currently selected item. For use on the cover.
     property JellyfinItem itemData
     // Id of the collection currently browsing. For use on the cover.
     property string collectionId
 
+    // Bad way to implement settings, but it'll do for now.
+    property bool showDebugInfo: false
+
     //FIXME: proper error handling
     Connections {
         target: ApiClient
@@ -98,6 +102,14 @@ ApplicationWindow {
         autoPlay: true
     }
 
+    PlaybackManager {
+        id: _playbackManager
+        apiClient: ApiClient
+        mediaPlayer: _mediaPlayer
+        audioIndex: 0
+        autoOpen: true
+    }
+
     // Keep the sytem alive while playing media
     KeepAlive {
         enabled: _mediaPlayer.playbackState == MediaPlayer.PlayingState