Handle cases where raw bytes in bytecode overflow u8

[kengorab]

In one Advent of Code problem, the bytecode vec was just so long that Jump instructions' offsets couldn't be calculated correctly, given that the offset is a u8 (max 255). This clearly needs to be fixed.

Note that the same issue likely applies for Constants too, or any other bytecode which expects an argument. This solution should be versatile enough to extend to those other situations as well.