Allow to add custom mapping from group names from oidc provider to nextcloud

Feature request

Which Nextcloud Version are you currently using: (see administration page)

Is your feature request related to a problem? Please describe.

Allow to add custom mapping from group names from oidc provider to nextcloud while keeping the access rules the same as before

This is mostly to be able to move the server from my association from the social_login app to user_oidc which had this feature and so that the migration can be as transparent as possible

Describe the solution you'd like

This is that we have there which maps access to certain gitlab suborganization to group ids with the sociallogin app.

groupMapping":{"sysadmin":"admin","teams\/kde-developers":"KDE Developers","teams\/kde-ev-board":"KDE e.V Board","teams\/akademy":"Akademy Team","teams\/kde-brazil":"KDE Brazil Members","teams\/kde-espana-board":"KDE Espana Board","teams\/kde-ev-fundraising":"KDE e.V. Fundraising WG","teams\/kde-ev":"KDE e.V Members","teams\/promo":"Promo Team","teams\/vdg":"Visual Design Group","teams\/gcompris-contributors":"GCompris Educators","teams\/community-wg":"Community Working Group","teams\/mentor-programs":"Mentor Program Members","teams\/german-environment-agency-projects":"German Environment Agency Projects","teams\/kde-eco-collaborators":"KDE Eco Collaborators"}

Describe alternatives you've considered
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Additional context
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