Session times need to be entered in a confusing way when Daylight Saving time starts/ends before the session date

[enricobattocchi]

Describe the bug

If you are e.g. in CET timezone and you try to create a session for a date after the start of Daylight saving time, the time you set will be displayed +1 hour in the Sessions overview list and in the schedule.
The opposite (-1 hour) happens if you are e.g. in CEST and you create a session for a date after the end of DST.
This means that you have to set times skewed ±1 hour in the editor to have the right result.

Looks similar to #748, but probably it's not been fixed by the related PR because in this case the timezone changes depending on the date.

To reproduce

Steps to reproduce the behavior:

1. Set the site to a timezone which uses DST, e.g. Rome
2. Enter the editor for a session
3. If you are testing in November to March, set a date in April to October, or viceversa. In other words, make sure there is a DST switch between your date and the session date.
4. Set the session time to 10:00
5. Publish the session.
6. Visit the Sessions overview in the backend, see that the session time is now 11:00 (or 9:00 in the second case)
7. Visit the Schedule page in the frontend, see that the session time is now 11:00 (or 9:00 in the second case)
8. Edit the session once more: the time will still be 10:00.

Expected behavior

I would expect to set the actual planned time for the session in the actual timezone of the date of the event, without the need for a calculation to display the right time.

Screenshots
The session in the editor, while editing it on December 2, 2022:

The same session in the overview:

The same session in the schedule:

WordCamp

Experienced both in https://italia.wordcamp.org/2022/ (sessions created in September for a November date) and https://torino.wordcamp.org/2023/ (sessions will be likely created in February for an April date).

System (please complete the following information):

• Device: Desktop
• OS: Devuan Linux
• Browser Firefox
• Version 107

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