add some useful CL action overview statistics to summary
add some useful CL action overview statistics to summary

BUG=None
TEST=`./gather_builder_stats --cl-actions --past-week`

Change-Id: I8aad81b3b73c2a2d21d426d66e490a033108d7e9
Reviewed-on: https://chromium-review.googlesource.com/190344
Reviewed-by: Aviv Keshet <178e8ae417efbe404feca7ab4cb8f0ba8c109369@chromium.org>
Tested-by: Aviv Keshet <178e8ae417efbe404feca7ab4cb8f0ba8c109369@chromium.org>
Commit-Queue: Aviv Keshet <178e8ae417efbe404feca7ab4cb8f0ba8c109369@chromium.org>

bpsinc-native/src_third_party_chromite,chadversary/chromiumos.chromite,bpsinc-native/src_third_party_chromite,bpsinc-native/src_third_party_chromite,chadversary/chromiumos.chromite