Description
Is your feature request related to a problem? Please describe
When using SAML SSO, users must be added to the 'admin' group on the IdP as any changes made locally to the Nextcloud instance will be overwritten when the users logs in. There is no way to change or map a group to the 'admin' group in Nextcloud within the instance. This means the backend must have a group called 'admin' which does not clearly indicate what the group is for as it is likely the IdP is shared between multiple applications.
Describe the behaviour you'd like
There should be in option in the SAML configuration to grant members of a Group admin rights to the Nextcloud application. This way the IdP could have a group such as nextcloud-admins be associated with members who should have admin rights to Nextcloud.
Describe alternatives you've considered
Currently you can create a group within your IdP called 'admin'. For example, if using Keycloak you can create a local group called 'admin' and map the user to that group (you can do this with Roles as well).
Additional context
This community topic also describes the issue
https://help.nextcloud.com/t/how-to-give-saml-users-admin-rights/115468