Add a random sample optimiser

[BradyPlanden]

Feature description

Add a simplistic random search optimiser, with the following API:

optim = pybop.RandomSearch(cost, sample_distribution=pybop.Uniform(0.5,0.7))

Motivation

Random search optimisation is useful for convergence benchmarking compared to more advanced optimisers. This issue is to add a simplistic random search based optimiser, with additional integration tests comparing the convergence of our current optimisers.

Possible implementation

Either use distribution provided by arguement, or the underlying parameter prior distributions.

Additional context

No response