Syntax update (#17465)

* Add RESPECT, IGNORE, NULLS, WAIT_AT_LOW_PROIRITY and AUTO_DROP

* Add BIT_COUNT, GET_BIT, LEFT_SHIFT, RIGHT_SHIFT and SET_BIT

* Add LEADING, TRAILING and BOTH

* Add DATETRUNC

* Add APPROX_PERCENTIL_CONT and APPROX_PERCENTILE_DISC. Remove AGGREGATE

* Add WEEK, QUARTER, HOUR, MINUTE, SECOND

* WITHIN GROUP

* Add DAY, MONTH, YEAR keywords

* BLOCKERS

* GROUP

* ARRAY and SCALAR

Author: Charles-Gagnon