Add Thread network HAL

Bug: b/203492431
Test: Build and run the VTS test and run otbr-agent on Android emulator.
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:b82b0478059dd6203f43d5917558e34fd4ed44d5)
Merged-In: If58b5a8c75e40376ae6c6e93554afe750496308b
Change-Id: If58b5a8c75e40376ae6c6e93554afe750496308b