C/C++/Rust implementation of Scaler's scheduler

[rafa-be]

A C, C++ or Rust implementation of Scaler's scheduler will have a few performance advantages, mainly by relying on a more efficient memory management, and by avoiding unnecessary copies of objects.

Contrary to the client and the worker implementation, re-implementing the scheduler in a language different from Python is less challenging, as it's not actively interacting with Python objects.

The scheduler is also the main scalability blocking piece, which makes its efficiency more critical in making Scaler more scalable.