cli: Relocated check subcommand to Gitaly binary
The gitaly-hooks check subcommand is used by admins to check whether the internal API of Rails is accessible. Since in a running system gitaly-hooks itself does not need to call the internal API this check makes more sense to reside in the Gitaly binary and has been moved there accordingly. This will validate whether or not Gitaly can actually call the internal API.
Updates to the documentation are made in !93493
Closes #4320 (closed)
Edited by Justin Tobler