Use git submodules instead of having the ci add youtube-dl

[nullket]

Currently youtube-dl is added during the package release within the ci.

This PR integrates youtube-dl (and youtube-dlp in prepartion to be used and integrated in a future PR) as submodules instead. The benefits are:

• Version control on the release side (and tested in development before)
• Your local plugin folder would (almost see below) resemble the release version
• The github action would only had to remove the .git folder, add the version etc. (like it already does right now)
• Adding or removing an alternate youtube-dl fork would be quite easy

Attention: @firsttris due to the github workflow using your kodi github repos (including tokens etc.) I was not able test the changes to the build-addon.yml and build-script.sh as well as the resulting addon zip file. But I did check the addon locally with the changes and the addon works perfectly (it still uses youtube-dl, the dlp fork is just already added to the lob folder)

[firsttris]

well done, from the logs of github action as well as from looking at the zip file i would say it worked like a charm.

These versions have been created:
https://github.com/firsttris/repository.sendtokodi.python3/blob/master/plugin.video.sendtokodi/plugin.video.sendtokodi-0.1.1445725605.zip
https://github.com/firsttris/repository.sendtokodi/blob/master/plugin.video.sendtokodi/plugin.video.sendtokodi-0.1.1445725605.zip