Fix implicit coercion of aggregation and window functions
Fix SHOW PARTITIONS

Connectors (such as the Hive connector) that return Slices for their TupleDomains ended up with the
toString() representation of Slice in SHOW PARTITIONS
Fix missing synchronization
Remove redundant (and incorrect) call in IndexManager

This was a left-over from a merge conflict
Merge operator stats atomically
Implement toString for hll
Fix Hive connector partition lookup

Use Slice.toStringUtf8() instead of .toString(). This fixes an issue where
all queries to the Hive connector that used a WHERE clause on a string
partition column would return no results.