[Feature request] Support basic git operation staged/unstaged.

[kgfly]

Please consider to add.

Select multi files on left pane. Stage/Unstaged them. Basically, match what https://github.com/sindrets/diffview.nvim offers.

Thanks.

[kgfly]

https://github.com/sindrets/diffview.nvim has become a dead project. Above is a blocker for folks to move from https://github.com/sindrets/diffview.nvim to this project. Thanks.