fix: local user setting change

[Schwehn42]

Description

With the introduction of the newly refactored settings dialog (#4265), it was made possible to add settings screens outside a board.

However, using this in other views, like the WIP template view (#4254) revealed that changing the user name or avatar would not be applied to the state until reloading the page.

The reason for this is simple: We use the features participants and auth separately, both of which contain information about the name and avatar of a user. The difference lies in where the information is available:

• auth.user is always available after the user has logged in
• participants.self is only available after joining a board.

The way these two change is also different:

• auth.user is initially retrieved after logging in and doesn't change.
• participant.self is updated when a server event is sent.

Thus, the solution is to apply the changes to the user (name and avatar specifically) so we aren't dependent on being in a board session. In places where user information is required, using auth instead of participants is required.

Changelog

• Use user state from auth feature instead of participants in settings.
• When editing the user in the settings dialog, changes are applied instantly to auth.
  • add auth action editUserOptimistically
  • adjust participants thunk editSelf

Checklist

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas

[laila-rin]

lgtm :)