Bring back author colors

[max-nextcloud]

Author colors were removed during the yjs rework. Bring them back.

Approaches:

• Either use awareness state and have each user announce their author colors and a list of segments they wrote similar to how the user cursor plugin works
• Or use a separate datastructure within the yjs document to maintain a list of authorship

[N07070]

Hello,

I was directed here from https://github.com/nextcloud/notes/issues/758#issuecomment-2682500116 .

I would like to pitch in and say that this feature would be very useful and help to make the usage of etherpad obsolete.