We should not use CustomWelcome field to store FileId.

[blkbee]

If we use CustomWelcome field to store FileId (for photo/video/doc welcome message), the FileId replaces the welcome text and the welcome message text will be the FileId. We should have separate field to store FileId and updates the welcome message methodology.

[RealAkito]

I will look into it, CC @ATechnoHazard as well.