This starts the metrics module, which will eventually offer facilities
to track metrics about a system, like average memory use, or other
performance counters.
Change-Id: I2b9dd089cbc2a15af295661fda6f8a6c30353d45
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/15441
Commit-Queue: Keir Mierle <keir@google.com>
Reviewed-by: Wyatt Hepler <hepler@google.com>
Reviewed-by: Ewout van Bekkum <ewout@google.com>
Reviewed-by: Fateh Singh <fsingh@google.com>
Reviewed-by: Zoltan Szatmary-Ban <szatmz@google.com>
