feat: implement vc-api issuer interfaces

[toannvit]

Issue

• RFC-0031: Implement vc-api interfaces for issuer and verifier #92

Description

• Implement a plugin router implementing vc-api-issuer api interfaces
• RFC - https://github.com/uncefact/project-vckit/tree/main/rfcs/features/0031-vc-api

Changes

• Create plugin router (vc-api-issuer)
• Change the agent.yml file to expose issuer apis

Test results

[arpentnoir]

@toannvit

• no need to add scope to pr name or commit messages - we are not using them, we may eventually, but it means even more granular commits than already is the case with just CC type. if we do end up adding scopes to commit message structure, then I think RFCs are a good option, but we'd probably make a mapping from short scope name to RFC. for now just standard conventional commits without scope is fine.

• it doesn't look like you are mapping request and response structures, so requests are falling through to veramo defaults.
  i.e. vc-api has an "options" object, but veramo function expects root level proofFormat, keyRef, etc...

• I think these routers should all go in a single package - vc-api - rather than their own packages.