[Feature]: Expose username {{user}} for templates

Feature detail

It would be good to make {{user}} available in the template configuration to enable the separation of photos better when having multiple users.

This would allow some configurations like:

{{user}}/{{y}}/{{MM}}/{{filename}}

While I have not looked at the code, implementing this should be easier than trying more complex solutions.
The more complex solution could have a configurable parameter attached to the user profile (defined by the admin, possibly pulled in from an SSO parameter). If this is empty, it could fall back to the username.

Platform

Web