Pytree regularizer strength

[BalzaniEdoardo]

Tree map the regularizer strength in the setter so that we can support very specific regularization (either a subset of paramter or individual coefficients

            strength = jax.tree_util.tree_map(lambda x: jnp.asarray(x, dtype=float), strength)  # float(strength)

We need to verify that all (solvers x regularizers x models) are compatible with a strength that is either:

• a scalar
• a pytree with scalar as leaves
• a pytree with arrays that matches the parameters