Default lp_degree of MultiIndexSet initialized from array

When initializing the MultiIndexSet using array, if the lp_degree is not explicitly specified, it is assumed to be 2.0 by default. This causes issue in the current version of Canonical poly with the result of any arithmetic operation being always a polynomial of lp_degree 2.0 because the resulting MultiIndexSet is initialized in this way.

• Can lp_degree be inferred from the array? If not, we should enforce that lp_degree must be specified when initializing with arrays.
• Can we define lp_degree if the multiindices are incomplete?

Minimal code to reproduce the issue:

import minterpy as mp
from numpy.testing import assert_equal

mi1 = mp.MultiIndexSet.from_degree(spatial_dimension=2, poly_degree=3, lp_degree=1.0)
mi2 = mp.MultiIndexSet(mi1.exponents)

assert mi1.lp_degree == mi2.lp_degree