[Feature Request] Add keybind to unskip the last skipped segment

[observeroftime01]

I think having a dedicated keybind to unskip the last skipped segment would be great.

This seems relatively easy to implement considering the chapter markings created, and in a way I can already to this by using a chapter seek keybind. This is not ideal however since I'd have to skip two chapters essentially (back to the end of the skipped chapter, then one more time to get to the beginning of the skipped chapter).

My lua knowledge isn't strong enough to create something like this, anyone have some ideas?

[selurvedu]

This could be trivially solved with the default mpv keybinding, Shift+Backspace (it can be customised via revert-seek in input.conf), but, unfortunately, mpv_sponsorblock performs the skip in such a way that revert-seek doesn't work (for me, at least).

Consider the alternative scripts listed in #74. Unfortunately, that doesn't work with alternative scripts either.