feat: issue SD-JWT encoded VCDM 2.0 Credentials

[nanderstabel]

Description of change

Adds VCDM 2.0 SD-JWT credential format support in agent_issuance.

• Added vc+sd-jwt format alongside existing dc+sd-jwt format
• Implemented full VCDM 2.0 SD-JWT credential creation and signing flow

Blocked by:

• feat: issue SD-JWT VC credentials #278

Links to any relevant issues

• https://www.w3.org/TR/vc-jose-cose/
• Missing credential format definition for w3c vc v2 with sd-jwt FIDEScommunity/DIIP#67
• Clarifications regarding SD-JWT in DIIP FIDEScommunity/DIIP#87
• add credential format profile for vcdm 2 with jose openid/OpenID4VCI#699

How the change has been tested

• Added the case::vc_sd_jwt test case to test_create_unsigned_credential

Manual testing:

1. run ssi-agent with the developer profile enabled
2. Validate the the Credential Issuer Metadata contains an "VCDM 2.0 SD-JWT" credential configuration:

curl --location 'http://localhost:3033/.well-known/openid-credential-issuer'

3. Create a new VCDM2.0 SD-JWT Credential:

curl --location 'http://localhost:3033/v0/credentials' \
--header 'Content-Type: application/json' \
--data '{
    "offerId":"001",
    "credentialConfigurationId": "VCDM 2.0 SD-JWT",
    "type": [
        "VerifiableCredential"
    ],
    "credential": {
        "credentialSubject": {
            "first_name": "Ferris",
            "last_name": "Crabman",
            "dob": "1982-01-01"
        }
    },
    "expiresAt": "never"
}'

4. Create the offer string:

curl --location 'http://localhost:3033/v0/offers' \
--header 'Content-Type: application/json' \
--data '{
    "offerId": "001"
}'

5. 'Scan' the offer with this specific UniMe version
6. Accept the Offer

Definition of Done checklist

Add an x to the boxes that are relevant to your changes.

• I have followed the contribution guidelines for this project
• I have performed a self-review of my own code
• 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
• New and existing unit tests pass locally with my changes
• I have successfully tested this change in a docker environment

[codecov-commenter]

Codecov Report

❌ Patch coverage is 45.94595% with 80 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
agent_issuance/src/credential/aggregate.rs	56.66%	52 Missing ⚠️
agent_issuance/src/state.rs	0.00%	22 Missing ⚠️
agent_issuance/src/server_config/aggregate.rs	0.00%	6 Missing ⚠️

Files with missing lines	Coverage Δ
agent_issuance/src/server_config/aggregate.rs	47.89% <0.00%> (ø)
agent_issuance/src/state.rs	43.75% <0.00%> (ø)
agent_issuance/src/credential/aggregate.rs	75.25% <56.66%> (ø)

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