gitlab-shell: add support for SSHUploadPackWithSidechannel

Depends on #1513 (closed)

Add the capability to use the new SSHUploadPackWithSidechannel RPC, added in #1513 (closed), to gitlab-shell. Gitlab-shell will only use the new RPC if told to do so by gitlab-rails. gitlab-org/gitlab-shell!557 (merged)
bump gitlab-shell version in gitlab-rails gitlab-org/gitlab!79128 (merged)

Edited Jan 26, 2022 by Jacob Vosmaer