gather_builder_stats: Refactor CL actions summary class in its own module.

This is a preparatory CL that splits out summarize_build_stats from
gather_builder_stats. The new module currently only contains the logic necessary
to summarize CL actions. This CL prepares the way to remove GS and spreadsheet
dependence from the script that summarizes CL actions.

TEST=(1) bin/summarize_build_stats --cl-actions \
             --cred-dir path/to/cidb/dir --past-week
     (2) bin/gather_builder_stats --cq-master --past-week
     (3) (updated) chromite unittests.

Change-Id: I690222a3e5d2c04fc9806f6eb0d48ec0b4ecce60
Reviewed-by: Aviv Keshet <>
Commit-Queue: Prathmesh Prabhu <>
Tested-by: Prathmesh Prabhu <>
5 files changed