fix: move away from Ganache-style returns

[itegulov]

I believe historically our JSONRPC API has been following Ganache style for method results. For example, this is the declaration for Ganache's evm_setAccountNonce:

evm_setAccountNonce(address: string, nonce: string): Promise<boolean>

It returns boolean that regulates whether the requested work was applied or not. As opposed to anvil's anvil_setNonce that returns nothing:

fn anvil_set_nonce(&self, address: Address, nonce: U256) -> Result<()>

We should follow anvil's approach here although the impact of this difference is most likely negligible.