* Add type for GitLab ProvisionToken
* Add default behaviour for domain
* Add IDTokenClaims for GitLab
* Add gitlab token source and token validator
* Thread GitLab support through auth and tbot packages
* Adjust cluster name fetching in token validator
* Initialize GitLab token validator in auth
* Improve comment on `sub`
* Working GitLab CI delegated joining
* Add additional token rule fields
* Add checking for new configuration fields
* add additional test cases for validation of gitlab config struct
* Add TestAuth_RegisterUsingToken_GitLab
* Add tests for IDTokenSource
* Fix imports
* Add tests for GitLab Token Validator
* Fix some comments that were incomplete
* Add license headers
* Move configuration from lib/service to lib/service/servicecfg
The new servicecfg package will hold only configuration for services.
This will allow other packages (like tctl and tsh) to depend on
servicecfg without pulling in all of lib/service (which has a number
of platform-specific details).
This is the first step towards being able to build tctl for Windows.
* Move PAM and BPF config into servicecfg
This breaks a compile-time dependency on BPF/PAM for tctl.