Add the protos for the traces used to publish metrics to Clearcut and
the anonymization code/test that ensure we don't collect de-anonymized
paths.
Bug: 326277821
Change-Id: Ifae4d51f59db2219995a0a8d21785729f5eeb137
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/5850298
Reviewed-by: Terrence Reilly <treilly@google.com>
Commit-Queue: Struan Shrimpton <sshrimp@google.com>