Use configurable ssh command and options everywhere

[pinpox]

• The configured ssh command was not used for secret deployment which has been fixed.
• REMOTE_SSH_OPTS are now used everywhere, not only for the nixos-rebuild command. This allows specifying custom ssh connection parameters, e.g. a non-standard port for SSH

[GeoffreyFrogeye]

I needed this and saw that it was still missing REMOTE_SSH_OPTS for deploy-flake. So I tried to add it myself: GeoffreyFrogeye@f93484c . Maybe there's a good reason for you not to do it that way, even though it worked for me. Otherwise, feel free to use :)

[pinpox]

I needed this and saw that it was still missing REMOTE_SSH_OPTS for deploy-flake. So I tried to add it myself: GeoffreyFrogeye@f93484c . Maybe there's a good reason for you not to do it that way, even though it worked for me. Otherwise, feel free to use :)

Nice, thank you! I added that one aswell.
This PR is ready to merge, I'm waiting for a bit of testing. Would you be able to test it with your setup and let me know if eveything works as expected?

Also, if you have other options that are missing and could be generally useful let me know!

[GeoffreyFrogeye]

Yes, it worked perfectly on my 3-machines setup. On those I'm using the standard SSH command, but using a non-standard SSH port.