Request: Support self-hosted GitLab instance for issue tracking and authentication

[ZenCorpDE]

I would like to use my own self-hosted GitLab instance for issue tracking and authentication.

If I understand correctly, it should be possible to specify a custom GitLab URL instead of using gitlab.com.

[mortondev]

It might be possible to use GitLab as a custom OIDC authentication provider already as per docs: https://docs.gitlab.com/integration/openid_connect_provider/ (Quackback supports custom OIDC providers), although for issue tracking that will require some changes to Quackback to support a custom URL. I'll try and have a look at this later in the week and will update once I know more.