feat: Add diff count to 'staged' and 'unstaged' titlebars

[evolvewithevan]

Is your feature request related to a problem? Please describe.
It would be very insightful to know the exact ++ and -- totals of staged and unstaged files for uncommitted changes, potentially even when viewing commits in the "Files changed" area

Diff count only currently exists when viewing diffs from specific files, not overall per commit.

Describe the solution you'd like
See attached screenshot for example of what it could look like.

Describe alternatives you've considered
diff count could also be listed near commit hash at the bottom right.

[JetpackDuba]

Hello!

Thanks for your suggestion, but I'm not really sure about it. What would be the benefit of such feature or what is it trying to solve?