Multiple srt subtitle files uploaded for each video

New feature. Multiple srt subtitle files uploaded for each video and subtitle selector in the Medial player Status: Not available. Should be implemented as soon as possible as a manual upload of SRT files on the fourth tab of the video upload dialogue. The player should allow the user to select the subtitles/captions of their choice.

Discussed and agreed in the UVic-Medial meeting of 24.10.25