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.

[stefanhaller]

@Wilfred Friendly ping; it would be awesome if you could take a moment to look at jesseduffield/lazygit#5732 and give your input if you have any.

I opened a draft PR (#1014) that shows what the difftastic changes would look like. It's only in draft mode because the spec is still in draft state, I'd otherwise consider it production ready. If you are not interested in spending time on this, that's totally fine; but would you consider merging that PR regardless? I'd otherwise have to maintain those changes in my fork and point lazygit users at it, which would also work but be a lot less convenient for everybody.