Description of the new feature/enhancement

I want the #2349 warning when pasting multiline text to a shell, but not when pasting to an editor that won't execute the lines as commands.

Proposed technical implementation details (optional)

Potential ways to detect such an editor:

• If the alternate screen buffer is active (regardless of whether it has been temporarily hidden by Peek behind Alternate Screen Buffer, like Flip Screen (Alt+F12) in mintty of Git Bash #6451). However, this heuristic would be fooled by less, which does execute lines starting with ! as commands.
• If bracketed paste mode (bracketed paste in conhost #395) is active. That would first have to be implemented. GNU Nano supports it.
• If any of the mouse tracking modes is active.

Whichever heuristic is used, there is a risk that the editor is killed and the modes are left active. Perhaps the configuration should have a separate opt-in for each heuristic.