Daylight savings time transition results in incorrect time for backdated checkin

Overview:
When you backdate checkin for a locale that has a daylight savings time transition, the checkin time is incorrectly calculated if the date falls before the transition (e.g., if it is currently DST and you backdate to before the DST transition).

Steps to Reproduce:

1. Log into https://folio-snapshot-core.dev.folio.org
2. In the "Settings" app, set the tenant time zone to a time zone with DST (e.g. America/New_York)
3. In the "Check in" app, set the checkin date to a date previous to the last DST transition in that time zone

Expected Results:
Checkins should reflect the time set in the "Check in" app

Actual Results:
Checkins are offset by 1 hour. Inspection of network requests shows that the checkin date/time is sent with the current offset from UTC, not the offset in effect on the checkin date.

Interested parties:
dbottorff