Add support for recursive blame

[kanielrkirby]

This Pull Request closes #2194.

It changes the following:

• Replace BlameFilePopup.blame: Option<BlameProcess> with BlameFilePopup.blame_stack: Vec<BlameProcess>. This involved changing any references to it, which happened to be a fair amount.
• Add keybinding for going back to a previous blame (b).
• Make keybinding for blame (Shift+B) work in the popups/blame_file.rs view, where it will take the commit and open a blame from that.
• Add hints for blame and back keybindings in blame_file.
• (edit) Add recursive blame feature to popups/file_revlog.rs

I followed the checklist:

• [ ] I added unittests (can add if you think it's necessary)
• [x] I ran make check without errors (this reached the same point master does, which fails on test_pre_commit_py. Does this need an issue?)
• [x] I tested the overall application (used it to make these commits! Haha)
• [x] I added an appropriate item to the changelog

[extrawurst]

Thanks for tackling this. I only had one comment or request to rework. Would love to add this feature

[extrawurst]

lets fix the ci, and i noticed that when the popup is open the command bar goes blank, that seems wrong

[kanielrkirby]

lets fix the ci, and i noticed that when the popup is open the command bar goes blank, that seems wrong

Will get on that when I get a chance! Appreciate the update.

[kanielrkirby]

Ah, that makes sense. So, to clarify, do you want to a) have somewhat of a non-popping stack, b) just nix the back functionality altogether, or c) did you have something else in mind?

Also @extrawurst I'm not sure if you saw my other comment, but I needed some more info.