Send Gitaly Repository with /api/internal/allowed

What does this MR do?

Adds Gitaly Repository to the payload from POST /api/internal/allowed

Adds 2 new feature flags, :gitaly_ssh_upload_pack and :gitaly_ssh_receive_pack

UPDATE GITLAB_SHELL before merging (gitlab-shell!139 (merged))

Are there points in the code the reviewer needs to double check?

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

gitaly#124 (closed)