Unroll ergonomics

[neysofu]

This is a PR draft to discuss loop unrolling ergonomics in the context of the SVM ABI encoder. Future changes and/or PRs might address the SVM decoder in a similar fashion if we're satisfied with these changes. The underlying tone of the refactor is:

• Replace the overwhelming number of macro-based impl's with type safety using Rust traits. We might have to tweak trait names and implementation algebra a bit more, but I think this looks better and is much simpler to deal with.
• Unify trait implementations for numeric primitives using the num-traits crate.
• Unroll loops using the seq-macro crate.
• Prune lots of code branches from the encoder logic by finding recurring patterns.

Possible TODOs and further changes to discuss:

• Naming of layout utility generators: which crate they go in and how to integrate them within the existing codebase.
• More comments and internal documentation.
• Evaluate similar decisions for the SVM ABI decoder

[YaronWittenstein]

If you can - please add a few more asserts to the other integer markers

[neysofu]

I'm not sure I understand, what other conditions should I test?

[YaronWittenstein]

There are more markers that can be asserted

[neysofu]

They are derived automatically form the 1B ones using arithmetic. I think all are covered