Adds the initial pw_chrono module to Pigweed with a facade for the
pw::chrono::SystemClock. In adition, the pw_chrono_stl module is
provided with the first STL based backend of said module by using
std::chrono::steady_clock.
Change-Id: Id29f4280aa399a81518f6d13183cf495b2ee72dc
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/23260
Reviewed-by: Ewout van Bekkum <ewout@google.com>
Reviewed-by: Wyatt Hepler <hepler@google.com>
Reviewed-by: Keir Mierle <keir@google.com>
Commit-Queue: Ewout van Bekkum <ewout@google.com>
