Copy operation files to relocate validation code

This change copies operation files ${operation}.cpp to
${operation}Validation.cpp and ${operation}.h in order to preserve
git history during the process of relocating validation code to its own
files.

The files were copied with:
$ croot && cd packages/modules/NeuralNetworks/common/operations
$ for file in *.cpp ; do cp "$file" "${file/.cpp/.h}" ; done
$ for file in *.cpp ; do cp "$file" "${file/.cpp/Validation.cpp}" ; done

And then:
* The preexisting .h files that were modified during the copy step above
  were restored to their previous code (via "git stash").
* The newly-created files (created from the copy step above) which
  include "Test" in their name were manually deleted.

This is part of a broader effort to relocate operation validation code
from libneuralnetworks_common* to neuralnetworks_types.

Bug: 191442336
Test: mma
Change-Id: I5b029f10e36b14ecd63ea293d587f7bb271019a3