sp_QuickieStore: Correct UTC offsets
Closes #449 by switching to use SWITCHOFFSET rather than our old arithmetic tricks with @utc_offset_minutes. I'll spin up some Docker containers on different time zones to provide more evidence that this is working. For now, I just have this screenshot from my British Summer Time instance.
Notice that the _UTC columns are unchanged. This is intentional and correct.
@erikdarlingdata As requested. Must've been my fault. Guess I synced with the wrong branch before forking.
More tests. I think this is the final proof that the code works.
Docker time zone "Pacific/Midway" (UTC -11:00)
Docker time zone "Canada/Newfoundland" (UTC -03:30, but I think it's their summer time)
Docker time zone "ETC/UTC" (UTC +00:00)
Docker time zone "Pacific/Guam" (UTC +10:00)