Support PostgreSQL datetime literal formats

[fulghum]

From PostgreSQL's date/time data type formatting reference:

Year-Month-Day [ Hour : Minute : Second ] [AD,BC] [ Timezone ] YearMonthDay [ Hour : Minute : Second ] [AD,BC] [ Timezone ] Month Day [ Hour : Minute : Second ] Year [AD,BC] [ Timezone ] where
Year is 4013 BC, ..., very large Month is Jan, Feb, ..., Dec or 1, 2, ..., 12 Day is 1, 2, ..., 31 Hour is 00, 02, ..., 23 Minute is 00, 01, ..., 59 Second is 00, 01, ..., 59 (60 for leap second) Timezone is 3 characters or ISO offset to GMT

  Date Examples:

• [x] Year-Month-Day – select '2024-10-31'::date;
• [x] Year-Month-Day – select '2024-OCT-31'::date;
• [x] YearMonthDay – select '20241031'::date;
• [x] YearMonthDay – select '2024Oct31'::date;
• [x] Month Day Year – select '10 31 2024'::date;
• [x] Month Day Year – select 'Oct 31 2024'::date;

  Discovered while testing the Pagila data dump