Add a basic depot_tools version information

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caused due to outdated depot_tools or actual unresolved bug.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/+/3541061
Reviewed-by: Aravind Vasudevan <aravindvasudev@google.com>
Reviewed-by: Gavin Mak <gavinmak@google.com>
Commit-Queue: Josip Sokcevic <sokcevic@google.com>
diff --git a/git_cl.py b/git_cl.py
index 51f1e97..715b982 100755
--- a/git_cl.py
+++ b/git_cl.py
@@ -5471,6 +5471,11 @@
   return 0
 
 
+def CMDversion(parser, args):
+  import utils
+  print(utils.depot_tools_version())
+
+
 class OptionParser(optparse.OptionParser):
   """Creates the option parse and add --verbose support."""