Add video transcription support

[vansisto]

Users should have the possibility to load a video file and get images from that video transcription.

So, there needs to be:

• Renew a diagram and update a picture
• Add functionality to the telegram bot server for retrieving video file
• Add one more converter, that converts video from telegram format to mp3
• Send ready mp3 file to a transcription
• Create UTs
• Merge

[vansisto]

I assume, that I can use FFmpeg for this too.