rationalize python and rust code

[bluegenes]

With the updated rust core, we need to go through and rationalize (and unify) rust and python code so we don't, for example, create sigs/zips that break rust assumptions.

from luiz: rust and python should support same ops. I started unifying a bunch of the code in https://github.com/sourmash-bio/sourmash/pull/2728/ but at this point that's very outdated