Implement SafeBytes and SnailTracer benchmark

This PR adds a new C++ contract and benchmark based on the SnailTracer Solidity contract, as well as a new SafeVar type for the bytes Solidity type (SafeBytes), derived directly from SafeVector (basically using a fixed std::vector<uint8_t> type instead of templates) and required as a return by some of the functions on SnailTracer.

There are two different SnailTracer contracts: the "original" one, using (u)int256 integers as per the Solidity original code (int = int256), and an "optimized" version that uses (u)int136 instead ((u)int128 and below seem to not be enough for the original contract's math logic, over/underflows happen every time).

Due to practical reasons, there's also a new raw() function on SafeTuple which does the same as get() on other vars (return the raw type beneath the class, since SafeTuple already has a get() that has its own functionality). This was implemented mostly because of SnailTracer, but can be used anywhere just like the other vars' get() wrappers.

AppLayerLabs / bdk-cpp

Implement SafeBytes and SnailTracer benchmark #129

Quality Gate failed