Add the build configuration and integrated test to generate a Python
distribution package named `tflite_micro` for publishing the tflm interpreter
as a Python module with a native extension.
Use the build tools provided in @rules_python, augmented by a custom rule
`py_namespace` for the reasons documented in `python/py_namespace.bzl`.
Provide an integration test at `//python/tflite_micro:whl_test`. Use a .tflite
model copied from the hello_world example. (Copied to avoid creating a
dependency.)
BUG=part of #1484
Ryan Kuester