Add PACK operation to NNAPI feature level 6.

Cherrypicked from Ic15d047b70c62437b4f0db6f2ca10127591ae07c

Bug: 206089870

Test: m -j NeuralNetworksTest_static
Test: VtsHalNeuralnetworksTargetTest

Change-Id: Ic15d047b70c62437b4f0db6f2ca10127591ae07c
2 files changed