Feature Request: Add group-add functionality from docker-compose to container creation.

[juvai]

Is your feature request related to a problem? Please describe

Repeating old issue: https://github.com/orgs/portainer/discussions/9832
I would like to see group-add support in portainer when creating a container with the add container button in the containers menu. The group-add feature in docker-compose gives you the option to add a user group to the container.

This is necessary to get gpu transcoding/hardware acceleration for jellyfin to work. Without this feature, only the cpu is used for transcoding, what results in choppy playback and dropped frames and makes this feature hard to use. The documentation for this feature of jellyfin can be found here:

https://jellyfin.org/docs/general/administration/hardware-acceleration.html

Describe the solution you'd like

A possible solution would be to add an extra section for it in the "Runtime & Resources" section in the container setup window. It should be possible to add mutiple groups for more complex projects.

Describe alternatives you've considered

The only alternative to this in portainer would be to use stacks, but there, the feature is also currently broken:

#6970

Additional context

Having this feature would allow the usage of hardware transcoding in jellyfin and it would also enable the usage of weaker hardware for it.