depot_tools has no versioning. It's hard to know if reported issues were
caused due to outdated depot_tools or actual unresolved bug.

This CL adds basic information about depot_tools version and it's
included in presubmit failure.

R=aravindvasudev@google.com, gavinmak@google.com

Change-Id: If8577c0826063693a7278a57a0cce629d4b1325f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/3541061Reviewed-by: Aravind Vasudevan <aravindvasudev@google.com>
Reviewed-by: Gavin Mak <gavinmak@google.com>
Commit-Queue: Josip Sokcevic <sokcevic@google.com>