fix(providers): ens::namehash with Unicode characters

[Sabnock01]

Motivation

ens::namehash doesn't correctly compute nodes for ENS names that contain Unicode characters as documented in foundry#5386

Currently, when providers::resolve_name is called on an ENS name like ret↩️rn.eth, it will produce a flawed node.
ethers-rs treats the nodes as sets of 32 decimal values that when converted into their hex equivalent, concatenated, and prepended with 0x, produce a node which is used to get the resolver contract for the ENS name.

# Currently, `ens::namehash` will return:
[58, 221, 97, 107, 77, 172, 118, 9, 34, 35, 212, 59, 68, 92, 73, 191, 217, 137, 183, 219, 23, 92, 60, 236, 100, 137, 88, 71, 201, 249, 185, 116]

# This will be converted to the invalid node:
0xadb545a232c011f5aa341c04e144e7ab15be672fe94cfea9138fc0b293229ad5

# The correct return value should be: 
[61, 229, 244, 192, 45, 182, 27, 34, 30, 125, 231, 241, 196, 14, 41, 182, 226, 240, 126, 180, 141, 101, 191, 126, 48, 71, 21, 205, 158, 211, 59, 36]

# which produces the valid node:
0x3de5f4c02db61b221e7de7f1c40e29b6e2f07eb48d65bf7e304715cd9ed33b24

Nodes can be verified through the ENS Registry contract's resolver and owner functions here.

Solution

The reason for the discrepancy is that ret↩️rn.eth was not being stripped of its trailing VARIATION SELECTOR 16 after the Unicode character. ENS ignores these but the namehash function did not account for them.

The namehash function has been modified to strip any VS16's thus enabling it to successfully resolve ENS names with emojis.

A test with the appropriate name has been added for verification.

PR Checklist

• Added Tests
• Added Documentation
• Breaking changes

[mattsse]

lgtm

wdyt @DaniPopes