Refactor MinHash implementations (many shared methods)

[luizirber]

The B-Tree impl in #1045 is a copy-paste-fix from the Vec impl. There is opportunity for refactoring and sharing most of the methods. Define a MinOps trait with what methods should be implemented, and add default impls when possible.

(punted from #1045 (comment))

[ctb]

this is another good first issue for people interested in getting into Rust, but it would need more description to be truly approachable, I think.

[ctb]

hi @luizirber still relevant?

[luizirber]

Yup, in #2728