Creates the pw_random module, starting it off with a random number
generator interface and an implementation based on the xorshift*
algorithm.
Change-Id: Ideda3eb9b713c586ce12230b8f572d079435d949
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/15362
Commit-Queue: Armando Montanez <amontanez@google.com>
Reviewed-by: Keir Mierle <keir@google.com>
