credential oa plugin

[toannvit]

Description

• The project vc-kit aim to support VCs created in different methods like w3c verifiable credential , open attestation. This ticket is to integrate Open Attestation . After this done , the vc-kit agent will have ability to issue , verify and sign the document under open attestation method.

Definition of Done

Pre-condition: you have a valid, raw (unwrapped) open attestation document, and have added the plugin to the agent config, and started the server. The raw document should contain issuer DID that is managed by your agent, and has an appropriate key created.

• Be able to post the raw payload to the remote agent and receive a signed OA document back.
• Be able to post the credential to the verifyCredentialOA endpoint and confirm that the credential is valid and all checks pass.
• Must be signed by key managed by the agent's KeyManager
  You'll need to include reference to key manager to use in the create method because an agent may have multiple key managers installed..