Create a `ReservoirComputingBenchmarks` library

[MartinuzziFrancesco]

It would be nice to provide a streamlined way to user for testing the models they build with RC.jl. I think setting up a library with some basic benchmark functionalities should be relatively quick and straightforward. Take RCBench as a reference point for the initial tasks:

• Nonlinear Transformation
• Nonlinear Auto-Regressive Moving Average
• Memory Capacity
• Nonlinear Memory
• Information Processing Capacity
• Sin(x) Approximation
• Kernel Rank
• Generalization Rank

Also I would need to update this issue linking the specific papers