Add support to header, is-gitlab-member for internal tracking
What does this MR do and why?
This change adds support for identifying GitLab team members in the workflow service.
A new flag called isGitlabMember is added to the configuration, which can be set via command line argument (x-gitlab-is-a-gitlab-member) or environment variable (DUO_WORKFLOW_GITLAB_MEMBER).
This information is then passed to the server through a new header called x-gitlab-is-a-gitlab-member in API requests.
The code reorganizes some flag declarations for better grouping and adds the necessary fields to the client metadata structure to support this new feature. Tests are also updated to verify the new header is properly set.
This change will allow the workflow service to provide different behavior or access levels based on whether a user is a GitLab team member.