bug(TXE): Error messages in nested calls don't bubble up

[LHerskind]

Currently if a failure happens in a nested call (foreign call) the error message will not be bubbling up.

For example, the following test will fail, but with an empty message instead of the expected.

#[test(should_fail_with="Balance too low")]
unconstrained fn transfer_private_failure_more_than_balance() {
    // Setup without account contracts. We are not using authwits here, so dummy accounts are enough
    let (env, token_contract_address, _, recipient, mint_amount) = utils::setup_and_mint(/* with_account_contracts */ false);
    // Transfer tokens
    let transfer_amount = mint_amount + 1;
    let transfer_private_call_interface = Token::at(token_contract_address).transfer(recipient, transfer_amount);
    env.call_private_void(transfer_private_call_interface);
}

Notably, if run just as a test #[test], you will get the following.

Failed calling external resolver. RPC error response: RpcError { code: -32000, message: "Assertion failed: Balance too low", data: None } 

So ideally it should be passing the first test.