The aggregation fuzzer lets us compare the results of queries between old versions of mongod and new versions to let us find query correctness bugs. Since allPaths indexes are particularly prone to causing correctness bugs, we should extend the agg fuzzer so that it compare query results between a mongod which has an allPaths index and a mongod which doesn't.

This will involve
1) Making some changes to the agg fuzzer repo (may need a TIG ticket)
2) Adding a .yml in buildscripts/resmokeconfig for the new mode