feat: multisig ed25519

[eranrund]

Description

This PR adds Ed25519 key support to the multisig contract.

Todos

• Unit tests
• Manual tests
• Documentation
• Connect epics/issues

Steps to Test

Run cargo test - happy to do any manual testing if you provide guidelines/instructions on how you approach that.

Expected Behaviour

The multisig contract should now support Ed25519 keys.

Other Notes

The multisig-prover contract is still hardcoded to Ecdsa keys. I am not sure if it is a priority to change that.

Linking to AXE-1900

[codecov]

Codecov Report

Merging #110 (b457283) into main (9f0a344) will increase coverage by 0.27%.
The diff coverage is 98.60%.

@@            Coverage Diff             @@
##             main     #110      +/-   ##
==========================================
+ Coverage   86.85%   87.12%   +0.27%     
==========================================
  Files         114      115       +1     
  Lines       11099    11372     +273     
==========================================
+ Hits         9640     9908     +268     
- Misses       1459     1464       +5     

Files	Coverage Δ
contracts/multisig/src/key.rs	91.03% <100.00%> (+5.55%)	⬆️
contracts/multisig/src/signing.rs	99.56% <100.00%> (+0.05%)	⬆️
contracts/multisig/src/test/common.rs	100.00% <100.00%> (ø)
contracts/multisig/src/types.rs	93.75% <100.00%> (ø)
contracts/multisig/src/contract.rs	98.56% <99.62%> (+0.03%)	⬆️
contracts/multisig/src/ed25519.rs	85.71% <85.71%> (ø)
ampd/src/handlers/multisig.rs	82.77% <0.00%> (-2.15%)	⬇️

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[cgorenflo]

I suggest some minor adjustments, otherwise looks good to me!