Add expiration_days in rotation_configuration for gitlab_group_service_account_access_token
Add expiration_days in rotation_configuration for gitlab_group_service_account_access_token, which is possible now that the API endpoint supports setting expiresAt.
If it looks copy-pasta'd from gitlab_group_access_token, that's because it is!
Needs a new release of client-go with gitlab-org/api/client-go!2153 (merged)
Documentation: https://docs.gitlab.com/ee/api/group_service_accounts.html#rotate-a-personal-access-token-for-a-service-account-user
Closes #6426 (closed).