Arrange the code in more flexible and circuit-friendly manner.

[nkaskov]

Traditionally, the design of zkEVM's code is derived from the proving logic. The building components of zkEVMs usually follow the logic of the circuit in terms of constraints. Since we are building the zkEVM from already existing source code, we do not want and do not need to change the code significantly. If we can make the required changes by adding new functionality to the zkLLVM frontend, we should take this path instead of changing the code. Though, sometimes, we still need to change the code structure. This issue aggregates all the known changes to be made.

• Rewrite instruction context dispatch in a more circuit-friendly manner #9
• Block parsing circuit-friendly algorithm #11
• Adjust storage struct to the assigner memory layout #12