Emit positionChanged when seeking with vlc backend
Reason for the change
It seems that vlc does not generate an event when calling libvlc_media_player_set_position, so we have to manually emit positionChanged. If the playback is paused and we don't manually emit this signal, then the rest of the app still believes we are at the old position, prior to the seek. This results in a bug where the position label does not update as the duration slider is manually moved.
Test plan
To test:
- build Elisa with vlc
- start playing a track
- pause the playback
- move the seek slider
Before MR: the position label is not updated (is updated when playback starts again though)
After MR: the position label is updated as the slider moves
Screenshots or screen recordings
| Before | After |
|---|---|
| before video | after video |