OSC-1717 support for better integration in lazygit

[stefanhaller]

Hi, I'm the current maintainer of lazygit, and I have come up with a custom OSC protocol that improves the user experience of lazygit when custom pagers are used; see jesseduffield/lazygit#5732 for information about that, including a video that explains what this is about. Your feedback would be very welcome!

[jesseduffield]

Hey @Wilfred, just adding my +1 to this: this change would make a substantial improvement to the user experience of all the Lazygit users who use difftastic as their pager.