Several roles or "personalities" per user

Description

I'd like to collect different "personalities" under a single user account. For instance, I may create a group or a project, and be "master" or "owner" for administrative tasks, but once the project is running, I want to be a simple "developer" or "guest", and not run into the risk of breaking things inadvertently (like pushing into protected branches). I don't want to create several user accounts, and I don't want to hide my name, I just want to use higher permissions only when I need them.

Proposal

• Give any user the possibility of creating personalities with lower permissions, globally or per-project/group.
• Make it possible to link ssh keys with personalities (so I can have a special key for when I want to act as "master").
• In the web interface add a dropdown menu or similar to select personalities (so I can become "master" just when I need to approve a MR)