Optimize full text search with a CTE

Optimize full text search with a CTE

The tsquery used directly in a JOIN was resulting in bad
plan with lots of nested loops and operations. Using a CTE
to define the query improves the plan.

Also, instead of ARRAY_AGG(DISTINCT foo), just return the
whole thing in an array. Not great for dupes, but we can
handle those inside search.query_parser_fts if we really
need to.

Signed-off-by: Dan Scott <dscott@laurentian.ca>