Improve DST handling in schedules

From slack:

According to the docs, when a cron is configured with local timestamp, we have the following behavior:
Beware Daylight Saving Time: If a Temporal Cron Job is scheduled around the time when daylight saving time (DST) begins or ends (for example, 30 2 * * *), it might run zero, one, or two times in a day! The Cron library that we use does not do any special handling of DST transitions. Avoid schedules that include times that fall within DST transition periods.
Is there any plan to implement something like DST transition policies, along the line of:

• duplicate_dst: RUN_FIRST, RUN_LAST, RUN_NONE
• missing_dst: SHIFT, SKIP
  or something like this that would control the behavior of Temporal Schedules in the case of DST transitions?

If not configurable, maybe make the default the most intuitive one, i.e. de-duplicate and shift missing run.
It's the default behavior of Airflow.

Start with the Temporal Schedule documentation and the cron library behavior described in the issue. Determine how DST duplicate and missing times currently behave, then define whether configurable policies or intuitive defaults are desired. Done requires an agreed policy and corresponding implementation scope; the issue names no files or tests.