Contract.allFrom abstract solidity contracts

[3Nigma]

Permit loading of abstract contracts even though, by default, this won't result in any byteCode being generated by the Solidity compiler.

So, for example, the following solidity contract:

abstract contract SimpleStorage {
    uint public num;

    function set(uint _num) public {
        num = _num;
    }

    function get() public view returns (uint) {
        return num;
    }
}

even though all of its methods have an implementation, will result in its solo.evm.bytecode.object being ''. Even though it will correctly extract the ABI.

We are allowing this mostly so that the ContractRegistry is able to get generated correctly when bundling (it only needs the ABI in this scenario).

When this is the case, be sure not to allow uploading of the Contract through a ApiSession in an attempt to make it live.