Add Internal CMAES implementation

[BradyPlanden]

Feature description

This issue is intended to lay the groundwork for #274. An internal implementation of CMAES is required so that we can have direct access to the adapted covariance matrix. I'm currently planning to use pycma for this, as it has the API requirements to do what we need, and has proven to be performant on the battery problems we've encountered so far.

Motivation

Provides PyBOP with better acces to the CMA-ES attributes, including covariance and convergence information

Possible implementation

Follow the groundwork laid out in #319 and #316

Additional context

No response