wip: integration testing

[Lusitaniae]

Integration testing with solana-test-validator to run local single node cluster and test gRPC all from the Github Actions

• Need to whitelist new action: JarvusInnovations/background-action@v1
• May need to build/download agave/grpc builds in the future

TODO:

• If we make the cluster reproducible we could check that all the gRPC requests/subscriptions return the exact data we expect
• Matrix testing between one or more gRPC versions against multiple Agave versions?