[proposal] Add Support for Issue Credential DIDComm Protocol

[nickreynolds]

Is your feature request related to a problem? Please describe.
Currently, there is no good, standard way to interface with issuers and request credential issuance in Veramo

Describe the solution you'd like

• An implementation of the "Issue Credential 3.0" DIDComm protocol, as described here: https://didcomm.org/issue-credential/3.0/

• Implementation should include utility functions for creating message types, message handlers for processing / saving messages, and anything required to maintain the "state machines" described in the protocol. This should include any "optional" messages such as "Propose Credential".

• Message handlers should support both automated processing of messages (according to a provided policy, like is done in the Coordinate Mediation 3.0 protocol implementation) as well as user-intention processing (e.g. the received message is saved and the next step of the state machine is not initiated until the user reviews it and takes action)

• Implementations should respond correctly when receiving an "impossible" message (e.g. one that does not fit into the state machine).

• Implementation should have significant test coverage (i.e. > 90%) and exercise the test vectors specified here: https://github.com/decentralized-identity/waci-didcomm/tree/main/test/vectors

notes

• Some implementation details (such as payment decorators) should be considered optional. If not implemented, please leave a //TODO in the appropriate places
• This specification originated in the Hyperledger Aires community. If there are any parts of the spec that are unsupported by Veramo, they can be left unimplemented (but leaving a //TODO is apreciated)

[nickreynolds]

originally proposed here: #1106

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.