Make a new trait, `InfluxRpcTest`, that types can implement to define
how to run a test on a specific Storage gRPC API. `InfluxRpcTest` takes
care of iterating through the two architectures, running the setups, and
creating the custom test step.
Implementers of the trait can define aspects of the tests that differ
per run, to make the parameters of the test clearer and highlight what
different tests are testing.
Carol (Nichols || Goulding)
Marco Neumann