Improved OIDC authentication

[H3xaChad]

Improve OIDC Authentication

Summary:

• Simplified Configuration: Now only requires wellKnownURL to auto-fetch OIDC endpoints.
• Claim Merging: Added mergeIdTokenClaims option to merge claims from the ID token with the user profile.

Why:

• Easier Setup: Reduces configuration complexity by leveraging OIDC discovery, also lowering the risk of misconfiguration
• Accurate Group Mapping: I actually had massive issues with the group mapping, because with Azure Entra ID the 'roles' claim used to assign roles/groups is inside the ID token. But since the ID token is ignored it was impossible to get this working.

One dependency was added (jwks-rsa) since it is mandatory to verify the ID token

Hope you find some time to look into the PR give some feedback! :)

[NGPixel]

What if the oidc server doesn't have a .well-known endpoint? It should still allows to specify the endpoints manually.