Datepicker wrong days labels for UK user timezone and website US timezone near UK DTS period.

[MaksVeter]

Description

The DatePicker calendar displays wrong date labels for users in UK when the website is in US tz.
All Day's labels are shifted by 1 back. Doing the debug - found that the issue happen because of two libs (date-fns and moment.js) used in Gutenberg works differently with Day Saving Time switches. The date-fns is used for defining start of week, month etc. when moment is used as main lib to works with dates.
So when getting calendar array with dates from date-fns - the calendar contain dates in different timezones before and after DTS. So moment.js don't care about it and think it's in the same timezone.
This is similar issue to #56844 and #47698

Step-by-step reproduction instructions

1. Set local UK timezone
2. Set website US timezone (America/New_York)
3. Go to post with Gutenberg enabled
4. Open the post date picker
5. find the October 2024 and November 2024
6. Check the day's labels

Screenshots, screen recording, code snippet

Screen.Recording.2024-12-02.at.14.34.07.mov

Environment info

• WP 6.5, default Gutenberg version for this WP version (Also checked on the 6.7.1, 6.6.2)
• Chrome Version 130.0.6723.70 (Official Build) (x86_64)
• Mac OS 14.5 (23F79)

Please confirm that you have searched existing issues in the repo.

• Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

• Yes

Please confirm which theme type you used for testing.

• Block
• Classic
• Hybrid (e.g. classic with theme.json)
• Not sure