Add git support to utilize stashing to manage ephemeral reference changes

[SmeeK153]

Added steps to utilize git stash if the underlying solution is in git control in order to stash any changes made before switching references, and restore those changes after switching the references back in order to leave a more sanitized environment after toggling the references.

[RicoSuter]

Maybe we should put this behind an option (ie checkbox in the ui) so that the extension also works for users without git?

[SmeeK153]

I think that is definitely a much better way to go; assuming less about what the default behavior should be for the user.

[SmeeK153]

@RSuter, take a look and let me know what you think of the check I added.