make time updates work for .mpv and .avp

- time update notifications work for both backends
- only init mpv timers when mpv is the active backend
- move notification extension to playerbackend

Model/Player/Backends/AVPlayerBackend.swift

@@ -116,6 +116,10 @@ final class AVPlayerBackend: PlayerBackend {
         #endif
     }
 
+    deinit {
+        NotificationCenter.default.removeObserver(self, name: .getTimeUpdatesNotification, object: self.currentTime)
+    }
+
     func bestPlayable(_ streams: [Stream], maxResolution: ResolutionSetting) -> Stream? {
         let sortedByResolution = streams
             .filter { ($0.kind == .adaptive || $0.kind == .stream) && $0.resolution <= maxResolution.value }
@@ -596,6 +600,8 @@ final class AVPlayerBackend: PlayerBackend {
             if self.controlsUpdates {
                 self.updateControls()
             }
+
+            NotificationCenter.default.post(name: .getTimeUpdatesNotification, object: self.currentTime)
         }
     }
 

Model/Player/Backends/MPVBackend.swift

@@ -183,11 +183,17 @@ final class MPVBackend: PlayerBackend {
 
     init() {
         clientTimer = .init(interval: .seconds(Self.timeUpdateInterval), mode: .infinite) { [weak self] _ in
-            self?.getTimeUpdates()
+            guard let self = self, self.model.activeBackend == .mpv else {
+                return
+            }
+            self.getTimeUpdates()
         }
 
         networkStateTimer = .init(interval: .seconds(Self.networkStateUpdateInterval), mode: .infinite) { [weak self] _ in
-            self?.updateNetworkState()
+            guard let self = self, self.model.activeBackend == .mpv else {
+                return
+            }
+            self.updateNetworkState()
         }
     }
 
@@ -624,7 +630,3 @@ final class MPVBackend: PlayerBackend {
         }
     }
 }
-
-extension Notification.Name {
-    static let getTimeUpdatesNotification = Notification.Name("getTimeUpdatesNotification")
-}

Model/Player/Backends/PlayerBackend.swift

@@ -154,3 +154,7 @@ extension PlayerBackend {
         }
     }
 }
+
+extension Notification.Name {
+    static let getTimeUpdatesNotification = Notification.Name("getTimeUpdatesNotification")
+}