#8142 Allow more configuration of types of checkout commands
Different deployments of Allura may not always want the RW/RO/HTTP or RO/HTTP choices. E.g here on forge-allura.a.o it's all the same "https://" checkout command no matter what. And on local docker or development setups, perhaps only a file:// checkout is available and nothing else.
Changes on db/8142 as well as the forgehg repo with the same branch name.
QA:
Confirm checkout commands work in various configurations (check git/hg/svn and auth/anon) and display of the commands is good. Also spot-check commands on the empty repo instructions. And merge request instructions.
Merged.