[telemetry] Add script to manage files in Cloud Storage.

Particularly useful:
$ tools/telemetry/cloud_storage ls -r .
Tells you whether files in the cwd are public or Google-only.


BUG=340449
TEST=tools/perf/run_benchmark list; tools/telemetry/cloud_storage ls -r tools/perf

Review URL: https://codereview.chromium.org/147913005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249920 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 249920