feat: add eth_get_transaction_count to kakarot

[ClementWalter]

Feature Request

Describe the Feature Request

As per the RPC spec, an entrypoint to retrieve the nonce of an account

[FriendlyLifeguard]

Hello, can I attempt this one?

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[obatirou]

Do we want to push it for mainnet ? As there is discussion for migration for cairo1, do we want to add this entrypoint now ?

Pseudo implementation: In kakarot.cairo:

// @notice The eth_getTransactionCount function as described in the spec
//         see https://ethereum.org/en/developers/docs/apis/json-rpc/#eth_getTransactionCount
//         This is a view only function, meaning that it doesn't make any state change.
// @param evm_address The address to get the transaction count from
// @return Transaction count of the address
@view
func eth_get_transaction_count{
    syscall_ptr: felt*, pedersen_ptr: HashBuiltin*, range_check_ptr, bitwise_ptr: BitwiseBuiltin*
}(evm_address) -> (tx_count: felt) {
    Helpers.assert_view_call();
    let tx_count = Kakarot.fetch_tx_count(evm_address);
    return (tx_count=tx_count);
}

In library.cairo

    // @notice Fetches the transaction count of an account
    // @param evm_address The address of the account
    // @return The transaction count
    func fetch_tx_count{syscall_ptr: felt*, pedersen_ptr: HashBuiltin*, range_check_ptr}(
        evm_address: felt
    ) -> felt {
        let starknet_address = Account.get_starknet_address(evm_address);
        let (tx_count) = IAccount.get_nonce(contract_address=starknet_address);
        return tx_count;
    }

Interface needs to be updated

Note: RPC needs to take into consideration potential pending transaction and add one to the result if needed