mu4e-actions.el: make git apply patch history aware

As you are often applying a series of patches to a tree it doesn't
make sense to move the user to default-directory every time.

However there is another use case which I'm struggling to work with at
the moment which is dealing with a whole thread of patches. On most
mailing lists there tends to be a series of patches and it would be
useful to mark the whole thread (T->ag?) and action a whole set of
messages at once. Doing this manually for a 40-50 patch series is a
bit of a pain ;-)

I suspect the action should receive a list of messages so some
pre-processing can be done, for example sorting based on subject to
patches are applied in correct order.

Any idea for the best way to do this with mu4e?