Fix/DST issues (#7462)

* use the organizer timezone and invitee timezone to show slots

* type fixes

* set start date on selected TZ on booking payload

* add considerations when only the invitee is on DTS

* Apply suggestions from code review

Co-authored-by: alannnc <alannnc@gmail.com>
Co-authored-by: Omar López <zomars@me.com>

* fixes typo

* Apply suggestions from code review

Co-authored-by: alannnc <alannnc@gmail.com>

* cleaning

---------

Co-authored-by: Alex van Andel <me@alexvanandel.com>
Co-authored-by: Omar López <zomars@me.com>
Co-authored-by: alannnc <alannnc@gmail.com>

apps/web/components/booking/pages/BookingPage.tsx

@@ -426,8 +426,8 @@ const BookingPage = ({
     } else {
       mutation.mutate({
         ...booking,
-        start: dayjs(date).format(),
-        end: dayjs(date).add(duration, "minute").format(),
+        start: dayjs(date).tz(timeZone()).format(),
+        end: dayjs(date).tz(timeZone()).add(duration, "minute").format(),
         eventTypeId: eventType.id,
         eventTypeSlug: eventType.slug,
         timeZone: timeZone(),