Aditya Manthramurthy f04f8bbc78 Add support for Timestamp data type in SQL Select (#7185)
This change adds support for casting strings to Timestamp via CAST:
`CAST('2010T' AS TIMESTAMP)`

It also implements the following date-time functions:
  - UTCNOW()
  - DATE_ADD()
  - DATE_DIFF()
  - EXTRACT()

For values passed to these functions, date-types are automatically
inferred.
2019-02-04 20:54:45 -08:00
..
2018-10-23 09:44:20 -07:00
2018-10-31 14:15:27 -07:00
2017-02-10 11:51:41 -08:00