Machine Learning Attacks - Asset.Model

[gdbassett]

Should we add an asset of 'Model' as a way of delineating when an action is taken against a machine learning model rather than our normal assets. This may help compare the attacks against ML vs not ML, even if the action varieties come from the same action categories.

That said, we may not want to add a major enumeration so early without evidence of enough ML attacks to justify it.