Bug 35906: Add bookable option on itemtype

Bug 35906: Add bookable option on itemtype

Actually new "booking" feature can be set on an item but no directly on
an itemtype. This patch adds this possibility.

Test plan:
1) Test this new feature on an item as it were currently working.
2) Apply this patch
3) Run updatedatabase.pl
4) Reload Schema by running update_dbix_class_files.pl
5) Change new syspref 'item-level_booking' to 'itemtype'
6) Edit an itemtype, there is a new checkbox to add 'bookable' option
7) Test it with item with this itemtype, if there is 1 item at least you
   will see 'Booking' tab.
8) You can change syspref to 'item' to see the current behavior

Note: When item-level_booking is set on 'itemtype' you can change
dropdown option to 'No' on item bookable option.

Sponsored by: Association de Gestion des Œuvres Sociales d'Inria (AGOS)
Signed-off-by: Esther <esther@bywatersolutions.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Paul Derscheid <paul.derscheid@lmscloud.de>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>