What this PR changes/adds

First impl of DCP credential request API:

• Introduced DcpIssuerSelfIssuedTokenVerifier for validating the SI token from the participant
• Introduced DcpIssuerService for running the attestation pipeline and validation after SI token verification
• Introduced CredentialRuleDefinitionEvaluator for evaluating a list of CredentialRuleDefinition in an IssuanceContext
• Split issuance-credentials into two extensions issuerservice-issuance-attestations and issuerservice-issuance-rules for supported attestations and rules
• Added a DcpIssuanceApiEndToEndTest for testing the credentials request API
• Introduced a property edc.issuer.id for configuring the issuer DID (might be temporary)

Why it does that

dcp credential requests API support

Further notes

Left out in this PR:

• Rule and Attestation Validators
• Mapping validation (we might validate the mapping upon receiving a request)
• Presentation Query on Issuance
• ExternalApprovalPredicate (if the issuance process should be automatically approved)
• In DcpIssuanceApiEndToEndTest the attestation source is mocked.

Who will sponsor this feature?

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Linked Issue(s)

Closes #553

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