fix consistency of room naming of dms when a nickname for the user is set

[dozro]

Also use the nickname for the user in the room header for more consistency

Description

I saw the neat feature of giving people nicknames and noticed that the room name of a dm still is the non-nickname-room name. I wanted to fix this for more consistency.

Without the change (the version currently deployed)

With the change

Fixes #

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings

[7w1]

looks good, thank you for contributing!