[pallet-revive] implement the gas price API (#6954)
This PR implements the EVM gas price syscall API method. Currently this is a compile time constant in revive, but in the EVM it is an opcode. Thus we should provide an opcode for this in the pallet. --------- Signed-off-by: Cyrill Leutwiler <[email protected]> Signed-off-by: xermicus <[email protected]> Co-authored-by: command-bot <>