Add support for seeking with milliseconds

Needed for the media notification seekbar in jellyfin-android (available on Android 10+).
The relevant change needed in jellyfin-android is already merged.

src/scripts/inputManager.js

@@ -201,6 +201,9 @@ import appHost from 'apphost';
             'rewind': () => {
                 playbackManager.rewind();
             },
+            'seek': () => {
+                playbackManager.seekMs(options);
+            },
             'togglefullscreen': () => {
                 playbackManager.toggleFullscreen();
             },