Updated jol to 0.2 to resolve the slow startup problem due to heavy GC
Add queries that fail before starting to expiration queue

This was a bug introduced in https://github.com/facebook/presto/pull/1917
Fix handling of null collections in unnest
Handle non-scalars in json_array_get
Precompute hashes for nodes that need hashes

1. Add abstraction for hash generation
2. Add an optimizer that uses optimized hash generation for all nodes
that use groupByHash and lookup source
3. Modify operator test to run for both with and without hash generation enabled
4. Add a config option and session property to turn the feature on/off
Make JsonType comparable