Add gitArgs as Cmd Argument

[scheeles]

This enables the possibility to set e.g. --no-pager flag

[capnfabs]

Wowwwwwww I didn't know that this was an argument to git and not to git diff!

Thanks for the PR, @scheeles! I'm going to finish a refactor of some internals in the coming week, and then will merge this after and release it into the next version.

I've got one outstanding UX question I'd like your thoughts on -- it seems to me that naming this gitargs is ambiguous in that it's unclear whether it's used for checking out certain commits (e.g. git [gitargs] checkout) or for the diff command (the change you've made for this PR here).

What do you think instead about a UX where you supply the gitargs and the diffargs and the diff statement in one argument instead? e.g.

• instead of grouse --gitargs='--no-pager' --diffArgs='--stat'
• this: grouse --diffCmd='--no-pager diff --stat'?

I see pros and cons to both approaches.

[capnfabs]

Otherwise, it looks like there's only a handful of these program-level args that would be relevant for grouse, I guess we could just add --no-pager as an argument to grouse directly. 🤔

[scheeles]

Not sure if --diffCmd='--no-pager is misleading, but I am fine with adding only --no-pager.

[capnfabs]

Alright, merged this + will refactor to take the --no-pager argument directly. Thanks for your contribution!