Make NNAPI Version more structured -- hal

Prior to this topic, NNAPI Versions were linear and represented by an
enumeration. However, this did not properly account for the
non-linearity of runtime-specific features such as a control flow
operations with operands of dynamic sizes. This topic alters Version to
be a struct containing a feature level enumeration as well as a boolean
which indicates whether there are runtime-specific features.

Bug: 206975939
Test: mma
Test: NeuralNetworksTests_static
Change-Id: I78c54ef597bf269b137f2835332bdedac49883d4