Use company_working_plan hours instead of hardcoded hours

[tm8544]

Instead of using hardcoded start end end hours for working_plan_exceptions, it would be better to use company_working_plan start end and hours for that weekday. when resetting the form. Company plan is the baseline where the user is making an exception.

[tm8544]

If the weekday in question is not in the company_working_plan, then hardcoded values 08:00 and 20:00 are used.
Otherwise company_working_plan hours are used.

7c4660a handled only the resetTimeSelection, as caba8b5 handles also editing.

[tm8544]

Added c3ed328
When editing working plan exception, if the date changes, old exception needs to be deleted before saving on the new date, otherwise exception on the old date remains on the calendar (and editing with date change is like copying).