Add tests to jsonrpc, to assure our jsonrpc clients behave as expected.

[msf]

This validates the following:

• for a given "stack", we do exactly a specific set of jsonRPC calls, with specific arguments.
• the response jsonRPC client returns is a simple concatenation of the responses of those calls, in a predefined order.

for the case of arbitrum-nitro, it also validates the correct extraction of the transaction hashes from the eth_getBlockByNumber response. this is trivial, but still good to validate.