Move all op preparation functions to OperationsUtils.

  - All op operations are moved to OperationUtils.
  - Add a helper function to derive implict padding scheme from
    explicit paddings.
  - Make all prepare function return false when seeing error.

Bug: 63905942
Test: NeuralNetworkTests
Change-Id: I16538dbd731a5ca1e6de5e0d0b269e9f386f4d29
12 files changed
tree: b4ebfa6320e9e3e247ac3307873a7a1c61dbca68
  1. nn/
  2. Android.bp