Introduce SimpleMerkleTree & migrate to ethers.js

[Amxx]

Fixes #30
Partially Fixes #13

This PR:

• Replaces previous tooling with ethers.js
  • Core now support BytesLike (hex strings and Uint8Arrays)
  • All values are returnes as hex strings (proofs, leaf hashes, ...)
• Fixe the Bytes (now BytesLike) compare function. (See Compare bytes does not correctly compare array of different length #30)
• Introduce a SimpleMerkleTree (in parallele to the existing StandardMerkleTree)
  • No encoding
  • Leafs are all BytesLike with length 32bytes
  • Provides the same interface as StandardMerkleTree, with the exception of leafHash which is irrelevant
  • This can be used to in conjunction with a custom hashing function to represent trees that don't do the recommanded double hashing.

Rational:

Merkle tree have been built using other tools before this library was available. Some of these trees do not use double hashing, and are thus not representable using the existing StandardMerkleTree class. This prevents devs that have to deal with these trees from using this library.
The goal is NOT to encourage not using double hashes. StandardMerkleTree should be prefered for new trees. The goal is to provide a migration path to user that would want to manipulate old trees with this new library.

TODO

• Documentation

[frangio]

Using the ethers package increases the installation size from 7.2M to 24M... I would not do that. It's heavy and a lot of people are using Viem now, so I think it would be better for this library to stay agnostic.

We can install the bytes utilities only with the package @ethersproject/bytes. Note that it's Ethers v5 code but it should be fine.

[Amxx]

Is there an easy way to check the install size of a package you are working on ?

[frangio]

Not that I know of. I did npm pack and then installed the tarball in a fresh directory after npm init -y.

---

Is there an issue with native bigint?

[Amxx]

Is there an issue with native bigint?

The issue is that I don't think about them

[Amxx]

Replaced by #36