MRG: refactor sketching utilities

[bluegenes]

• refactor for reusability: move all generalized sketch building utils --> utils/buildutils.rs
• do minor refactoring to use sourmash::encodings::HashFunctions for moltype, created Abund enum.
• requires MRG: derive Hash for HashFunctions sourmash#3344 to use Hash for sourmash::encodings::HashFunctions

Related:

• consider using sourmash core ComputeParameters instead of BuildParams #113

[bluegenes]

@ctb ready for review. No big changes, mostly just moved existing implementations.

[ctb]

Not sure how to sequence this with sourmash-bio/sourmash#3344 (review), but I think the simplest might be to target latest on sourmash and then before a release of directsketch will cut a new release of sourmash. Seem ok?

Alternatively, can just let it hang for a bit until we release new version of sourmash.

[bluegenes]

I'm going to target latest and drop it in main for now so I can put up other PRs off of it. I'm not in a hurry for release - no functionality changes here (or currently planned). But I'll make a draft PR to update to the next sourmash core release.

[ctb]

I'm going to target latest and drop it in main for now so I can put up other PRs off of it. I'm not in a hurry for release - no functionality changes here (or currently planned). But I'll make a draft PR to update to the next sourmash core release.

sounds good! we'll be in more of a hurry for a sourmash release over in branchwater once I get the MultiCollection PR figured out ;)