Deny unknown fields in the JSON-RPC layer

[fvictorio]

The JSON-RPC layer shouldn't accept parameters with unknown fields. This might cause some projects to start throwing errors, either because they are making a mistake or because we are missing some field. But in both cases, finding out about it is a good thing.

See https://github.com/NomicFoundation/hardhat/pull/4869 for the PR that temporarily removed this behavior.