Issue: https://gitlab.com/gitlab-org/gitlab/-/issues/336618

Gitaly deprecated and removed Namespace Service, we can remove
a repository instead

The allowed commands must be scoped to namespaces:

- git push/pull/archive
- git lfs authenticate

GitLab Shell detects that the passed key is a certificate and
requests /authorized_certs instead of /authorized_keys endpoint

This explicitly imports gitaly v16 instead of v15 and removes the
old one from `go.mod`.

Prior to this change personal access tokens without a ttl would never
expire. In Gitlab 15.4 we deprecated non-expiring tokens and are
scheduled for removal in 16.0.

https://gitlab.com/gitlab-org/gitlab/-/issues/369122

This change alters the gitlab-shell command for creating tokens to
ensure add a default limit of 30 days.

Closes https://gitlab.com/gitlab-org/gitlab-shell/-/issues/640