Add support for custom names in conversations for other users

How to use GitHub

• Please use the 👍 reaction to show that you are interested into the same feature.
• Please don't comment if you have no relevant information to add. It's just extra noise for everyone subscribed to this issue.
• Subscribe to receive notifications on status change and new comments.

Feature request

**Which Nextcloud Version are you currently using: version 31

Is your feature request related to a problem? Please describe.
My main issue is when using nextcloud for home use I don't want to have to set my name on nextcloud to be "Dad" for my kids on nextcloud.

Describe the solution you'd like
I would like to see a setting in the conversation settings to configure a "nickname" for another user such as with any other messaging platform with a private, custom nickname for another user.

Describe alternatives you've considered
I tried looking up the issue but I was unable to find any other ways to get around the issue of being unable to set a custom name but, I did find quite a few other people struggling with the same issue.

Additional context
The feature could just be a cosmetic change to the mobile app if need be but I would like to just be able to have a comparable alternative to using signal with their custom nicknames feature.

No files, tests, or entry points are identified in the issue. First clarify whether custom names belong in the web or mobile conversation settings, whether they are private per-user data, and how they should appear; done means the agreed interface supports setting and displaying another user's custom name without changing their account name.