drill

9ba4af86 - DRILL-5481: Allow to persist profiles in-memory only with a max capacity

DRILL-5481: Allow to persist profiles in-memory only with a max capacity 1. Introduced an InMemoryStoreProvider with the ability to maintain a max capacity 2. DrillbitContext now explicitly has a profileStoreProvider that, by default, re-uses the general PersistentStoreProvider, unless it is InMemory, which is when #1 is used. 2. Cleanly separated out QueryProfileStoreContext 3. Converted literal values to constants within ExecConstants 4. Updated drill-module.conf for default capacity closes #834