Add ability to specify a cert and key for gitlab connector

[bputt-e]

Preflight Checklist

• I agree to follow the Code of Conduct that this project adheres to.
• I have searched the issue tracker for an issue that matches the one I want to file, without success.

Problem Description

Our gitlab instance requires a valid cert/key when communicating to it (PKI infrastructure) and as it stands, we're not able to use the gitlab connector because of this

Proposed Solution

Add in a tls section to the connector config where we can specify the ca, crt, and key. This would be a compliment to #1542

tls:
  ca: /path/to/file.crt
  crt: /path/to/file.crt
  key: /path/to/file.key

Alternatives Considered

No response

Additional Information

No response

[nabokihms]

@bputt-e thanks for the feature request. I think it is another case to add to our unfinished construction issue #1635

I am also interested in this feature, yet for another connector - OIDC.

[jbgcarnes]

👍 For this feature, similar issue is stopping my team from using Dex as well. @nabokihms as #1635 is still nebulous, is dex open to a gitlab specific implementation? happy to make the MR if the project is.