This commit introduces a new feature to the commit view, allowing users
to filter commits based on the author's name or email address. Similar
to the existing path filtering functionality, accessible through <c-s>,
this feature allows users to filter the commit history by the currently
selected commit's author if the commit view is focused, or by typing in
the author's name or email address.
This feature adds an entry to the filtering menu, to provide users with
a familiar and intuitive experience
This allows to do the equivalent of "git rebase --onto <target> <base>", by
first marking the <base> commit with the new command, and then selecting the
target branch and invoking the usual rebase command there.
We've been sometimes using lo and sometimes using my slices package, and we need to pick one
for consistency. Lo is more extensive and better maintained so we're going with that.
My slices package was a superset of go's own slices package so in some places I've just used
the official one (the methods were just wrappers anyway).
I've also moved the remaining methods into the utils package.
