Implement VEX document verification system with issuer management and signature verification

- Added IIssuerDirectory interface for managing VEX document issuers, including methods for registration, revocation, and trust validation.
- Created InMemoryIssuerDirectory class as an in-memory implementation of IIssuerDirectory for testing and single-instance deployments.
- Introduced ISignatureVerifier interface for verifying signatures on VEX documents, with support for multiple signature formats.
- Developed SignatureVerifier class as the default implementation of ISignatureVerifier, allowing extensibility for different signature formats.
- Implemented handlers for DSSE and JWS signature formats, including methods for verification and signature extraction.
- Defined various records and enums for issuer and signature metadata, enhancing the structure and clarity of the verification process.

src/Web/StellaOps.Web/test-results/.last-run.json

@@ -1,4 +1,4 @@
-{
-  "status": "passed",
-  "failedTests": []
+{
+  "status": "interrupted",
+  "failedTests": []
 }