Add READ_ONLY flag to contract call function (#4418)
This PR implements the `READ_ONLY` flag to be used as a `Callflag` in the `call` function. The flag indicates that the callee is restricted from modifying the state during call execution. It is equivalent to Ethereum's [STATICCALL](https://eips.ethereum.org/EIPS/eip-214). --------- Co-authored-by: command-bot <> Co-authored-by: Andrew Jones <[email protected]> Co-authored-by: Alexander Theißen <[email protected]>