Provide a Zephyr implementation of the pigweed modules and facades
required for using pw_rpc in a Zephyr application.
Change-Id: I6f148e7d85b338fcb7045460912d228f1785576c
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/67186
Reviewed-by: Keir Mierle <keir@google.com>
Reviewed-by: Paul Fagerburg <pfagerburg@google.com>
Reviewed-by: Wyatt Hepler <hepler@google.com>
Pigweed-Auto-Submit: Yuval Peress <peress@google.com>
Commit-Queue: Auto-Submit <auto-submit@pigweed.google.com.iam.gserviceaccount.com>
