Had some tests for hash join types other than inner.
Add tests for the several type-related problem cases.
Rework how key-comparables and collators are passed to the hash join operators.
Use these properly and in a way that isn't confused by slightly varying types.
Another types-related test.
Row hash table only optionally matches nulls.
I missed that there was a test explicitly checking for incorrect behavior. Fix it.
merge MMcM: Some type-related issues with hash joins

Merge pull request #1455 from MMcM/sql-layer/hash-join-2
https://github.com/FoundationDB/sql-layer/pull/1455