Fork caching bug

[cptartur]

When using forking, fork_state_reader in

starknet-foundry/crates/cheatnet/src/state.rs

Line 70 in fd18c58

self.dict_state_reader

is used as a fallback for all dict_state_reader methods.

This is a problem because it is possible for dict_state_reader to return error for local contracts, where it doesn't make sense to fallback to fork state. For example: when calling and uninitialized storage key, dict_state_reader will return an error. Then, request to fork_state_reader will be made and only after it fails, default value will be used. This way, we are making an request to the RPC that is not cached and that doesn't make sense in the first place, because the contract is local.

Update the code to prevent not-cached request to the RPC in state.rs.

Either we do not fallback to RPC if the contract is only defined locally (could be tricky to check) or update the fork-state_reader logic to cache these kind of requests.