Bug 22272: Calendar: When entering date ranges grey out dates in the past from the...

Bug 22272: Calendar: When entering date ranges grey out dates in the past from the start date

In "Calendar" tool it's possible to pick dates before start
date as end date.

This patch sets end date calendars "minDate" as picked start day
to grey out past dates. Also reindents datepicker code for
better readability.

Test plan:
- Apply this patch
- Set start date from first calendar
- Set end date from second calendar
=> Dates before start date are greyed out

Signed-off-by: Nadine Pierre <nadine.pierre@inLibro.com>
Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
(cherry picked from commit 06e28c3ac5b708ce01ea1265fa993c1f85e98645)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>