Add Duo Code Review as a configurable option for Model Selection
Once Duo Code Review is migrated to AIGW (https://gitlab.com/gitlab-org/gitlab/-/issues/501321+), Add Duo Code Review as a configurable feature:
The steps are similar as SHM
- adding it to configurable enum - https://gitlab.com/gitlab-org/gitlab/blob/master/ee/lib/gitlab/ai/feature_settings/feature_metadata.yml
- The feature metadata https://gitlab.com/gitlab-org/gitlab/blob/master/ee/lib/gitlab/ai/feature_settings/feature_metadata.yml
model.yml and unit_primtives.yml are covered in https://gitlab.com/gitlab-org/gitlab/-/issues/538445+
issue