chore: nest install under go subcommand

[eh-am]

Move pyro-ci install to pyro-ci go install.

Reason is that install is (currently) only relevant to go, so it doesn't make sense having it at the second level.
Also if we want to add more commands to the go subcommand, like an go exec with clever go logic, with this approach it's easier to move forward. This is the reason for go install as opposed to install go.