Allow users without "Manage Server" permission to change username for the server and/or automatically populate it base on the email/username.

[skel0]

When and administrator removes the permission "Manage Server" for a group, the users in that group are now allowed to create/edit servers:

Basically they can't do right-click on the server to change any of the server's properties:

The problem with that is that the administrator, who is sharing pre-configured servers to the users, can only provide a "shared username" which is common for all users. If the users don't have the "Manage Server" permission then they can't change to their own username.

My proposal is to provide a drop-down list in the server's properties general tab, so the administrator can choose between these options (maybe could be more):

1. Fixed: user name is always the same for all users, this is the current behavior (the shared user name)
2. Email: pgAdmin will use the user's email to connect to the database so it will change for every user automatically. This binds with another feature request I made to make pgAdmin allow Entra ID authentication using the tokens: Enable Entra ID authentication for PostgreSQL servers in pgAdmin #9261
3. Ask: request the user to introduce the username and optionally save it.

Thanks!

JL.