qt/qml: SMPTE Timecode integration
This was actually meant to be added a while ago, but it had to wait until the toolbar control handling refactor.
It uses the smpte timer api that was added to the backend (player) two years ago.
I tried to follow the same approach that was used for player timer integration.
@tguillem, if you want and if you have time you can also make a quick review as afaik it is based on your work :)
Related: #22818 (closed), #16105 (closed).
Edited by Fatih Uzunoğlu