tflite: Extract native handle utility from ahwb

The same native handle utility might be reused by delegates.

This also simplifies the already lengthy implementation of
hardware_buffer.cc a bit.

BUG=b:305999697
TEST=bazel run --config=host_clang '//android:hardware_buffer_test'

Change-Id: Ia4865058b57dd988859a9f4bcfd65c54938dbc30
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/tflite/+/5449329
Reviewed-by: Ching-Kang Yen <chingkang@chromium.org>
Commit-Queue: Ching-Kang Yen <chingkang@chromium.org>
Tested-by: Ching-Kang Yen <chingkang@chromium.org>
Tested-by: Shik Chen <shik@chromium.org>
Auto-Submit: Shik Chen <shik@chromium.org>