feat(expr): fix PostgreSQL timestamptz subtraction error on Daylight Saving

[xiangjinwu]

https://github.com/postgres/postgres/blob/REL_16_0/src/backend/utils/adt/timestamp.c#L2714

	 *	This is wrong, but removing it breaks a lot of regression tests.
	 *	For example:
	 *
	 *	test=> SET timezone = 'EST5EDT';
	 *	test=> SELECT
	 *	test-> ('2005-10-30 13:22:00-05'::timestamptz -
	 *	test(>	'2005-10-29 13:22:00-04'::timestamptz);
	 *	?column?
	 *	----------------
	 *	 1 day 01:00:00
	 *	 (1 row)
	 *
	 *	so adding that to the first timestamp gets:
	 *
	 *	 test=> SELECT
	 *	 test-> ('2005-10-29 13:22:00-04'::timestamptz +
	 *	 test(> ('2005-10-30 13:22:00-05'::timestamptz -
	 *	 test(>  '2005-10-29 13:22:00-04'::timestamptz)) at time zone 'EST';
	 *		timezone
	 *	--------------------
	 *	2005-10-30 14:22:00
	 *	(1 row)

The idea is to introduce a correct expr variant timestamptz_sub (any internal name), and a session config DST_BUGFIX (visible to user, name TBD):

• When DST_BUGFIX is set to false (or postgresql), the frontend binds - operator between 2 timestamptz to existing variant subtract.
• When DST_BUGFIX is set to true (or precise), the frontend binds to the new variant timestamptz_sub.

	PostgreSQL-compatible variant	new variant
'2005-10-30 13:22:00-05'::timestamptz - '2005-10-29 13:22:00-04'::timestamptz	1 day 01:00:00	25:00:00
'2005-04-03 13:22:00-04'::timestamptz - '2005-04-02 13:22:00-05'::timestamptz	23:00:00	23:00:00

In this way, the interval returned always have no month or day. It also allows lossless transformation into Duration in rust and protobuf.

Additionally, tumble / hop shall also bind to either compatible variant or strict variant based on the session config.

Just writing the idea down without plan to implement it soon. We may prioritize it if we get any complains after the upcoming 25-hour day (Oct 29 in Europe and Nov 5 in the US)

[github-actions]

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