chromeperf: Add standard error and standard deviation to stats pipeline.
chromeperf: Add standard error and standard deviation to stats pipeline.

Bug: chromium:1202014

Change-Id: I2d94f1ea912cf8f7f29c7c48c70e42b287698955
Reviewed-on: https://chromium-review.googlesource.com/c/catapult/+/2858179
Reviewed-by: Dean Berris <34a37f59e4ade3cf49221306f04217acf3e86255@chromium.org>
Commit-Queue: Andrew Bennetts <f07c55753dac44d78e0294a1d64ea321baaa78f4@google.com>

catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult