Support configuring CI/CD token issuer

What does this MR do?

Support configuring CI/CD token issuer

• CI/CD token issuer can be configured by setting global.appConfig.ciIdTokens.issuerUrl.
• The config is rendered to Webservice and Sidekiq.

Related to this Omnibus MR - gitlab-org/omnibus-gitlab!8382 (merged)

Closes #6085 (closed)

Changelog: added

Related issues

Author checklist

For general guidance, please follow our Contributing guide.

Required

For anything in this list which will not be completed, please provide a reason in the MR discussion.

• Merge Request Title and Description are up to date, accurate, and descriptive.
• MR targeting the appropriate branch.
• MR has a green pipeline.
• Documentation created/updated.
  • https://docs.gitlab.com/ci/cloud_services/aws/?tab=Helm+chart+%28Kubernetes%29#configure-a-non-public-gitlab-instance
• Tests added/updated, and test plan for scenarios not covered by automated tests.
• Equivalent MR/issue for omnibus-gitlab opened.
  • Add issuer claim to configuration template file (gitlab-org/omnibus-gitlab!8382 - merged)

Reviewers checklist

• MR has a green pipeline on https://gitlab.com/gitlab-org/charts/gitlab.
• Consider downstream impact to the Operator, as per evaluating impact from changes to GitLab Chart.

Closes #6085 (closed)