[FEATURE] Introduce a ThirdParty GenericOIDC implementation.

[ghstahl]

Checklist

• I could not find a solution in the existing issues or docs.
• I agree to follow this project's Code of Conduct.

Description

I have a rough implementation for configuring in third party Generic OIDC and have tested it against Google and AzureAD.
Need to test it against Auth0, Okta, Ping and OneLogin. I don't see an issue there though as the only difference I have seen in the field is what scopes are to be sent.

i.e. AzureAd needs openid email profile User.Read

The hanko OAuth2 implementation that is used for the existing ThirdParty's (google, github, apple) is the same one being used with this as well. So, the OIDC is just there to discover the needed urls dynamically through a .well-known/openid-configuration endpoint.

i.e. accounts.google.com/.well-known/openid-configuration

Describe your ideal solution

This is my current config.yaml

third_party:
  redirect_url: http://localhost:8000/thirdparty/callback
  error_redirect_url: http://localhost:8888
  allowed_redirect_urls:
    - http://localhost:8888**
    - http://localhost:3000**
  providers:
    google:
      enabled: true
      client_id: 1096301616546-edbl612881t7rkpljp3qa3juminskulo.apps.googleusercontent.com
      secret: GOC**[REDACTED]**
    github:
      enabled: true
      client_id: e489eb4f05e9f247d8ad
      secret: 1bb**[REDACTED]**
  generic_oidc_providers:
    google_oidc:
      authority: https://accounts.google.com
      display_name: Google(Generic OIDC Provider)
      enabled: true
      client_id: 1096301616546-edbl612881t7rkpljp3qa3juminskulo.apps.googleusercontent.com
      secret: GOC**[REDACTED]**
      scopes: "openid profile email"
      require_provider_email_verification: true
    mapped_staff_oidc:
      authority: https://login.microsoftonline.com/590**[REDACTED]**/v2.0
      display_name: Mapped Staff (Generic OIDC Provider)
      enabled: true
      client_id: 3b918868-9bff-431f-bd9c-f9896d628e6b
      secret: hU4**[REDACTED]**
      scopes: "openid profile email User.Read"
      require_provider_email_verification: false
      hidden: true

Workarounds or alternatives

No response

Hanko Version

main

Additional Context

No response