bots: Allow Machine to ssh-connect to arbitrary machines
bots: Allow Machine to ssh-connect to arbitrary machines

Support different addresses, ports, identities.

Closes #10425
garrett/cockpit,moraleslazaro/cockpit,deryni/cockpit,moraleslazaro/cockpit,andreasn/cockpit,andreasn/cockpit,moraleslazaro/cockpit,cockpit-project/cockpit,andreasn/cockpit,garrett/cockpit,moraleslazaro/cockpit,cockpituous/cockpit,cockpituous/cockpit,andreasn/cockpit,deryni/cockpit,cockpit-project/cockpit,mvollmer/cockpit,martinpitt/cockpit,cockpit-project/cockpit,cockpit-project/cockpit,garrett/cockpit,martinpitt/cockpit,cockpit-project/cockpit,mvollmer/cockpit,mvollmer/cockpit,cockpituous/cockpit,garrett/cockpit,cockpituous/cockpit,cockpituous/cockpit,deryni/cockpit,andreasn/cockpit,cockpituous/cockpit,andreasn/cockpit,deryni/cockpit,moraleslazaro/cockpit,moraleslazaro/cockpit,moraleslazaro/cockpit,martinpitt/cockpit,martinpitt/cockpit,mvollmer/cockpit,deryni/cockpit,garrett/cockpit,andreasn/cockpit,deryni/cockpit,deryni/cockpit,mvollmer/cockpit,martinpitt/cockpit