Add multi-ledger support

[KimEbert42]

Add multi-ledger support to aries-akrida

[KimEbert42]

There are a few outstanding issues with adding multi-ledger support to aries-akrida.

The first, is that aries-akrida currently only supports a single issuer and a single verifier. I could see value in being able to add additional issuers and verifiers in a test. The biggest question is how to manage the configuration of each of the issuer and verifiers? It is possible that we move the configuration of the issuers and verifiers into Locust instead of using environment variables? The question is does this exist as a locust config file, or does each test specify its own definition of the agents?

The second issue, is that if aries-akrida uses a single issuer to use multi-ledger support is that the issuer cannot use two ledgers at once for writing. This means that when attempting to use write to two separate ledgers using the same Aca-Py agent, the agent can only write to ledger A, or ledger B at the same time. When the Locust test X and Locust test Y are at different stages of testing, Locust X and Locust Y may be attempting to write to different ledgers at the same time. This would likely cause one of the writes to fail. I don't recommend configuring a single Aca-Py agent to write to two ledgers at the same time, so we would need to use more than one issuer agent.

Next steps:

1. Add support for more than one issuer agent.
2. Add support for more than one ledger