HIP: AnonCreds Verifiable Data Registry

[sumapnair-ibm]

Draft PR #762 raised proposing support for AnonCreds in Hedera.

The objective of this HIP is to be able to build SSI solutions with Hedera as the Verifiable Data Registry and in the future potentially support migration of current pilots / older implementations to the Hedera network.
Enabling AnonCreds support on the Hedera network offers organizations and entities developing Self Sovereign Identity (SSI) solutions the opportunity to leverage the exceptional benefits provided by the Hedera Hashgraph Ledger.
Since AnonCreds is being re-architected to be ledger / data store agnostic for public artifacts, extending support for this implementation will encourage wider adoption of Hedera as the Verifiable Data Registry and promote interoperability with implementations that are not on the Hedera ledger.
With prominent council members such as IBM, Boeing, Standard Bank, and others expressing active interest, Hedera can serve as an ideal Verifiable Data Registry for these solutions.
This HIP proposes that requisite changes be made to enable Hedera so that solution builders can choose to use Hedera as a Verifiable Data Registry for AnonCreds implementations.