[feature] Add OIDC support

[Simon-Boyer]

Problem Description

I'm trying to use an identity provider which currently only supports OIDC, it would be nice if it was one of the supported options for omni.

Solution

Add OIDC as a third option to omni auth providers methods (currently only auth0 and saml).

Alternative Solutions

Tried to use this thing, but I cant make it work: https://github.com/IdentityPython/SATOSA/tree/master

Notes

No response