fix: plat-6888 aws kms signer issue

[zeljkoX]

Summary

This PR addresses issues related to the usage of the AWS KMS signer.

Fixes and Improvements:

• recover_public_key fix: Previously, only the value 0 was used for recovery, resulting in errors. This has been corrected.
• Public key normalization: The DER-encoded public key is now normalized to a low-S value to comply with standard requirements.
• Caching enhancement: Improved caching mechanism for the AWS KMS DER public key to enhance performance.

Testing Process

Checklist

• Add a reference to related issues in the PR description.
• Add unit tests if applicable.

[codecov]

Codecov Report

❌ Patch coverage is 33.33333% with 14 lines in your changes missing coverage. Please review.
✅ Project coverage is 92.6%. Comparing base (648a0f1) to head (700a57f).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/services/aws_kms/mod.rs	20.0%	12 Missing ⚠️
src/utils/secp256k.rs	66.6%	2 Missing ⚠️

❌ Your patch status has failed because the patch coverage (33.3%) is below the target coverage (90.0%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@           Coverage Diff           @@
##            main    #411     +/-   ##
=======================================
- Coverage   92.6%   92.6%   -0.1%     
=======================================
  Files        216     216             
  Lines      70950   70961     +11     
=======================================
- Hits       65751   65750      -1     
- Misses      5199    5211     +12     

Flag	Coverage Δ
integration	0.5% <0.0%> (-0.1%)	⬇️
properties	<0.1% <0.0%> (-0.1%)	⬇️
unittests	92.6% <33.3%> (-0.1%)	⬇️

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