* Support configurable verifiers for VC and VP

* Update Go version to 1.21.5

* Fix bug with conversion of public ED25519 public key to JWK
* Using caching JSONLD document loader for unit tests
* New HTTP endpoints for signing arbitrary data and fetching Vault keys as JWK
* Verify VC proofs before making VP proofs from VC
* Support generation and verification of multiple proofs per VC/VP