Issue dotnet#2991 for problem context and goals

FYI I left in DIYMark as debug convenience [drop before merge]
PK driven like most real-world scenarios [AK too wide etc]
request/sequential/random and caching [avoid r-trip] cases
20 methods = 3xRoji, 5xADO, 4xFind, 2xFirst,2xHybrid, 2xObj, 2xDict
perhaps investigate BM RunStrategy, MaxIterationCount, SimpleJob, ShortRunJob
Git stats
EfBench02.* results & my analysis, but needs fuller explanation and Dev guidance