--autodrop and drop!

["Kovacsics Róbert" <kovirobi@gmail.com>]

Hi,

I really like git's autosquash, it's super useful, especially with git
absorb. I use them while the MR/PR is in draft state and then do a
clean-up when it's ready to be reviewed. I sometimes also make commits
which shouldn't make into the final MR, so I was wondering about
adding the `drop!` equivalent (maybe with `--autodrop`, or just also
under `--autosquash`, but I'm leaning towards the former as sometimes
I might want to clean things up while still keeping the temporary
commits).

An example of where this is useful is when I'm making changes to the
CI, so I will be running more CI pipelines than usual and end up
caring about the speed of it. So I make a `drop! Ignore other CI jobs`
commit.

If it's something reasonably easy for me to do, and someone thinks
it's easier to put a couple of bullet-points on how to do it than do
it, then I would be happy to try and implement it myself*

*I cannot promise timeliness, effort as/when I have the energy, but
since I'm the one who cares about this feature I don't think that will
be a problem.

Thanks,
Robert