Return info object when using SR iterative solvers.

Created by: PhilipVinc

When using LazySR.solve()we where trashing the additional informations returned by the solver, such as number of iterations and whoever it converged or not, so this PR simply propagates the informations out, and stores them in a hidden field in the driver (maybe we should make this field public?) so that it can be logged with custom callbacks.

However... right now Jax linear solvers don't return that information! They say that eventually they will. So it's rather useless... But at least we get the correct api in place and as soon as they start giving us the info, Netket will support it.