Enable OSC52 automatically if connected via SSH

[jonas-w]

When connecting via ssh to a macOS host, helix still uses pbcopy+pbpaste as a clipboard provider instead of OSC52.
I think this is not a problem when the remote is a Linux host, as helix checks for WAYLAND_DISPLAY/DISPLAY environment variables, which are normally not set in an SSH session. (at least I never had problems with Linux remotes)

My enhancement would be to check for the $SSH_CONNECTION environment variable, and if this is set, it would use the FallbackProvider instead of pbcopy+pbpaste.
As I mentioned before, this seems to be only a problem if the remote is macOS, so it would probably be suffice to add this check to the macOS target of the get_clipboard_provider method.

[jonas-w]

I'd also be willing to open a PR for this.

[jpeeler]

I'd be willing to test and confirm said PR.

[hholst80]

Yes this seems to work just fine in Linux. No Wayland specific environment variables are passed via SSH and "+y will copy text to the system clipboard.