Implement EVM version in LASER

[GNSPS]

Description

After discussion through a different channel with the team decided to create this issue for tracking purposes.

Given that some hard-forks implemented somewhat significant changes to EVM execution there's a possibility that some of these are or may become pertinent to Mythril's analysis of said execution.

Much like the Solidity compiler, which targets the different EVM versions according to their capabilities, so could Mythril's execution layer and prevent possible bugs in the analysis.

[muellerberndt]

IMO the strategy should be to always be up-to-date with the current mainnet code by default.

It would be cool though to be able to switch to an upcoming fork to "peek into the future" so-to-say. That way, we could detect if any existing contracts become vulnerable due to the changes.