Bug 34440: Add itemtype selection to bookings modal

Bug 34440: Add itemtype selection to bookings modal

Whilst we still don't need to know the specific item we will need to
know the itemtype to be able to fetch the correct circulation rules for
adjusting the datepicker with lead and trail times.

This patch adds such a picker option. You should be able to select the
item or itemtype in either order.. selecting itemtype first will limit
the items list to options available (and 'Any item').. upon selecting a
specific item the itemtype selector should become disabled and reflect
the itemtype of the item selected.

Sponsored-by: Cuyahoga County Public Library <https://cuyahogalibrary.org/>
Signed-off-by: Kristi Krueger <KKRUEGER@cuyahogalibrary.org>
Signed-off-by: Paul Derscheid <paul.derscheid@lmscloud.de>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>