Added OWNERS file for trace store.
Added OWNERS file for trace store.

Review URL: https://codereview.chromium.org/1211933002

benschmaus/catapult,catapult-project/catapult-csm,benschmaus/catapult,modulexcite/catapult,catapult-project/catapult-csm,catapult-project/catapult,0x90sled/catapult,scottmcmaster/catapult,catapult-project/catapult,sahiljain/catapult,sahiljain/catapult,benschmaus/catapult,0x90sled/catapult,zeptonaut/catapult,danbeam/catapult,catapult-project/catapult,catapult-project/catapult,sahiljain/catapult,zeptonaut/catapult,sahiljain/catapult,modulexcite/catapult,SummerLW/Perf-Insight-Report,dstockwell/catapult,SummerLW/Perf-Insight-Report,catapult-project/catapult,sahiljain/catapult,scottmcmaster/catapult,0x90sled/catapult,catapult-project/catapult-csm,zeptonaut/catapult,benschmaus/catapult,danbeam/catapult,modulexcite/catapult,benschmaus/catapult,benschmaus/catapult,SummerLW/Perf-Insight-Report,catapult-project/catapult,scottmcmaster/catapult,SummerLW/Perf-Insight-Report,danbeam/catapult,catapult-project/catapult-csm,benschmaus/catapult,catapult-project/catapult,catapult-project/catapult-csm,sahiljain/catapult,danbeam/catapult,dstockwell/catapult,catapult-project/catapult-csm,SummerLW/Perf-Insight-Report,SummerLW/Perf-Insight-Report,dstockwell/catapult,catapult-project/catapult-csm,dstockwell/catapult