[feat] Support stashing

[Udayan853]

Problem to solve

Currently Diffium does not support git stash operations, so being able to

• Stash local changes
• View list of stash entries
• Load/Remove entries

Proposal

An interface that can be toggled (show/hide) similar to the one provided by existing branch switch hotkey(b)
The interface would provide the above described functionality

Alternatives considered

Another enhancement could be the ability to preview changes within a stash entry without loading it. However, I’m not sure to what extent this might be feasible.

Additional context

Branch switch overlay

[kubeden]

This is a good suggestion. Feel free to work on it. :)

[kubeden]

Also! viewing stashed changes is already implemented by #51. Please explore the implementation and build on top of it

[Udayan853]

This is a good suggestion. Feel free to work on it. :)

Sure,
Would you suggest to add this feature in the refactored version directly( #55 ) or should I add the feature to the existing codebase?