Adds just the proto files from the in-progress logging module.
Change-Id: Ibe8ca60aaaf053cdfb184ec8dd413da49fc3b288
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/18780
Commit-Queue: Prashanth Swaminathan <prashanthsw@google.com>
Reviewed-by: Keir Mierle <keir@google.com>