This eliminates the need for the FAILURE status codes in
PlanStage and PlanExecutor, and brings query execution's
error reporting more in line with that of the rest of the
server. It also makes it easier for future implementations
of PlanExecutor to comply with the interface.
* Changes resmoke.py to propagate --storageEngineCacheSizeGB as
--inMemorySizeGB when running with the InMemory storage engine.
* Changes the mongo shell to propagate
TestData.storageEngineCacheSizeGB as --inMemorySizeGB when running
with the InMemory storage engine.
* Sets --storageEngineCacheSizeGB=4 when running with the InMemory
storage engine in Evergreen.