fix: update signature encoding to follow JWS specification

[mineme0110]

Description:

The signed presentation for the credential request is DER-encoded, according to the JWS specification, the signature should not be DER-encoded. Instead, it should be a concatenation of R || S, Base64 URL-safe encoded (as per RFC 7515, Section 8.1)

(hyperledger-identus/cloud-agent#1541)

Alternatives Considered (optional):

Yes not follow the JWS and fix in cloud-agent to support both DER Encoded and JWS but will require handling both and wont benefit much, since it is JWT we should follow JWS spec

Checklist:

• My PR follows the contribution guidelines of this project
• My PR is free of third-party dependencies that don't comply with the Allowlist
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• I have checked the PR title to follow the conventional commit specification

[coveralls]

Pull Request Test Coverage Report for Build 14056150531

Details

• 19 of 38 (50.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.2%) to 75.378%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/pollux/utils/jwt/DER.ts	17	36	47.22%

Totals
Change from base Build 14056133001:	-0.2%
Covered Lines:	3445
Relevant Lines:	4378

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💛 - Coveralls

[elribonazo]

@mineme0110 mind retesting again? I've restored the function we had in the past to normalise the der signature into compact raw, should be working now!