Transaction signing is something that happens in a lot of places - this
PR introduces primitives for transaction signing in `transaction_utils`
such that we can use the same logic across web3/eth1/etc for this simple
operation.
`transaction_utils` also contains a few more "spec-derived" helpers for
working with transactions, such as the computation of a contract address
etc that cannot easily be introduced in `transactions` itself without
bringing in dependencies like secp and rlp, so they end up in a separate
module.
Finally, since these modules collect "versions" of these transaction
types across different eips, some tests are moved to follow the same
structure.
Since these types were written, we've gained an executable spec:
https://github.com/ethereum/execution-specs
This PR aligns some of the types we use with this spec to simplify
comparisons and cross-referencing.
Using a `distinct` type is a tradeoff between nim ergonomics, type
safety and the ability to work around nim quirks and stdlib weaknesses.
In particular, it allows us to overload common functions such as `hash`
with correct and performant versions as well as maintain control over
string conversions etc at the cost of a little bit of ceremony when
instantiating them.
Apart from distinct byte types, `Hash32`, is introduced in lieu of the
existing `Hash256`, again aligning this commonly used type with the spec
which picks bytes rather than bits in the name.
Jacek Sieka