3349e1db1 (#9618) limited OSC 52 to SSH/mosh so a desktop terminal that ignores
it no longer reports a false success. That also disabled the only clipboard
route for containers and WSL without WSLg, which have no display to gate on.
Emit OSC 52 again on display-less Linux. On WSL, write the Windows clipboard
through PowerShell (verified, no OSC 52 size cap), preferring OSC 52 in
Windows Terminal where it is known to work. Desktop sessions with a display
still report the failure.
closes#9688