chore(code/starknet): Change signature scheme from ECDSA to Ed25519

[romac]

Closes: #XXX

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PR author checklist

For all contributors

• Reference GitHub issue
• Ensure PR title follows the conventional commits spec

For external contributors

• Maintainers of Malachite are allowed to push changes to the branch

[romac]

@ancazamfir Should I rather target this PR to #868 or do we merge to main directly?

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 82.31%. Comparing base (486f9cf) to head (bd42b53).
Report is 1 commits behind head on main.

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #871      +/-   ##
==========================================
+ Coverage   82.06%   82.31%   +0.25%     
==========================================
  Files         188      187       -1     
  Lines       16102    16060      -42     
==========================================
+ Hits        13214    13219       +5     
+ Misses       2888     2841      -47     

Flag	Coverage Δ
integration	82.16% <ø> (+0.22%)	⬆️
mbt	8.43% <ø> (+0.07%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
core	∅ <ø> (∅)
engine	∅ <ø> (∅)
app	∅ <ø> (∅)
starknet	∅ <ø> (∅)

[ancazamfir]

@ancazamfir Should I rather target this PR to #868 or do we merge to main directly?

I think this one can go to main.

[ancazamfir]

lgtm