This is an early version of the `pinpoint` client for starting Telemetry A/B experiments.

R=nodir@chromium.org

Change-Id: Iff11f8a16f93172cf71d9f76b02c27bd3b659111
Bug: chromium:1175615
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2703000
Auto-Submit: Dean Berris <dberris@chromium.org>
Reviewed-by: Nodir Turakulov <nodir@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@google.com>
Commit-Queue: Dirk Pranke <dpranke@google.com>