Refactor jankrate into LoopSummary

First and last loops are now ignore for certification.

Added target percentile to indicate the percentage of frames that meets
target requirement.

Percentile is now calculated by sorting the entire list of frame times.
It's less efficient, but makes modifier and getting various stats easier.

Test: Updated LoopSummaryTest and MetricSummaryTest

Change-Id: Icd08516cfbee80614ef5d62fd76f663f5683f066
5 files changed