seperate stage/ustage all files keybindings

**Is your feature request related to a problem? Please describe.**
A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]
unstagging all files and then staged and unstaged files are combined and no longer able to retrieve staged changes.

**Describe the solution you'd like**
A clear and concise description of what you want to happen.
unstage all files can have different keybindings, "A" instead of "a"

**Describe alternatives you've considered**
A clear and concise description of any alternative solutions or features you've considered.
none...

**Additional context**
Add any other context or screenshots about the feature request here.
add more keybindings as well to search for file in staged/modified files. and a keybindings to jump to next/previous modified file.