Right-align thumbnails in bubbles

[dbrgn]

Right-align outogoing thumbnails inside the chat bubbles. It looks a bit ugly otherwise when the caption is long.

[dbrgn]

Or even better, limit the width of the chat bubble, if it contains a caption. It needs a min-width and a max-width.

[MustafaMulla29]

Is it still open? Can i work on this?

[threema-danilo]

@MustafaMulla29 in general, Threema Web is in maintenance mode (see note in the README: https://github.com/threema-ch/threema-web#threema-web). However, if the fix is small, a pull request with a fix would be welcome!