FR: Abort when splitting with all or no changes

[Vampire]

Is your feature request related to a problem? Please describe.
If I do a jj split and then change mind, I have to finish the split, specify two commit messages and then jj undo the split, this is a bit cumbersome.

Describe the solution you'd like
If the selection of changes to split away either contains all changes or no changes (i.e. one of the commits is empty),
I'd like to see this interpreted as aborting.
There is no real reason to do this intentionally, as you can simply use jj new -A to get the same result faster and more idiomatic.

[Vampire]

Also, the docs are wrong but should better be right.
They currently say

Splitting an empty commit is not supported because the same effect can be
achieved with jj new.

But this works, ist simply creates two empty commits as result without launching the diff editor.

[yuja]

Related: #5312 (comment)