experiment(PodcastPlayerView): add lock screen skipBackwardCommand/skipForwardCommand (15s)

Marks/Views/PodcastPlayerView.swift

@@ -128,6 +128,8 @@ final class PodcastPlayerViewModel {
         c.playCommand.removeTarget(nil)
         c.pauseCommand.removeTarget(nil)
         c.changePlaybackPositionCommand.removeTarget(nil)
+        c.skipBackwardCommand.removeTarget(nil)
+        c.skipForwardCommand.removeTarget(nil)
         try? AVAudioSession.sharedInstance().setActive(false, options: .notifyOthersOnDeactivation)
     }
 
@@ -224,6 +226,16 @@ final class PodcastPlayerViewModel {
             self?.currentTime = e.positionTime
             return .success
         }
+        c.skipBackwardCommand.isEnabled = true
+        c.skipBackwardCommand.preferredIntervals = [15]
+        c.skipBackwardCommand.addTarget { [weak self] _ in
+            self?.skipBackward15(); return .success
+        }
+        c.skipForwardCommand.isEnabled = true
+        c.skipForwardCommand.preferredIntervals = [15]
+        c.skipForwardCommand.addTarget { [weak self] _ in
+            self?.skipForward15(); return .success
+        }
     }
 
     private func updateNowPlaying() {