Add 1.2 NN HAL interface for dynamic output shape.

Let notify_1_2() notify output shapes.

Document unspecified dimensions and rank.

Bug: 73506513
Bug: 77234888
Test: NeuralNetworksTest_static
Test: VtsHalNeuralnetworksV1_xTargetTest with 1.2 sample driver
Change-Id: I01108913212d9f4aa47daf2f293ea19259925865