shell-integration: support OSC 133;A;click_events=2

[jcollie]

Kitty recently added support for sending relative (to the prompt) Y coordinates when clicking in a command prompt.

kovidgoyal/kitty#9500

[mitchellh]

I don't think there is any shell that actually supports this yet (it looks like the original proposer may be interested in trying to get zsh to eventually support it). So, no urgency here.