Add Postgresql Json Aggregate Function FILTER

[griffio]

Add JSON Aggregate Functions FILTER useful for working with schema-less column data (similar to #4703)

https://www.postgresql.org/docs/current/functions-aggregate.html

Add missing aggregate object functions

json_object_agg(key, value)
jsonb_object_agg(key, value)

Add json aggregate FILTER clause

SELECT json_agg(data) FILTER (WHERE (data->>'in_stock')::BOOLEAN) FROM SomeTable;

SELECT jsonb_agg(data->'color') FILTER (WHERE data ?? 'color') AS colors FROM SomeTable;

SELECT jsonb_object_agg(key, value ORDER BY key DESC) FILTER (WHERE key IS NOT NULL) FROM SomeTable;

SELECT jsonb_object_agg_strict(key, value) FROM SomeTable;

• Adds grammar changes
  • Case where expressions could be double colon casted
  • Case where aggregate functions take a table reference or column reference (function expressions only take a column reference)
• Adds fixture tests for grammar examples
• Adds integration tests

New Functions in Pg16 - strict functions are same as FILTER ... WHERE key IS NOT NULL except they fail with an error.

json_agg_strict
jsonb_agg_strict

json_object_agg_strict
jsonb_object_agg_strict

json_object_agg_unique
jsonb_object_agg_unique

json_object_agg_unique_strict
jsonb_object_agg_unique_strict

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• CHANGELOG.md's "Unreleased" section has been updated, if applicable.