Bug 9722: Allow users to add notes when placing a hold in opac

Bug 9722: Allow users to add notes when placing a hold in opac

The option of adding a note is controlled by new pref OpacShowHoldNotes.
This development is part of a larger one (see umbrella report 9721).

Test plan:
1 Verify if new pref is disabled by default. Place a hold. You can't add a note.
2 Enable the pref. Place a hold and add a note. Check in staff if you can see
the note in Catalogue Detail/Holds tab.
3 Toggle SingleBranchmode, AllowHoldDateInFuture/OPACAllowHoldDateInFuture,
OPACShowHoldQueueDetails, or OPACItemHolds.
Check the display of columns when placing a hold from opac.
4 Place a few holds with notes from opac search results in one run (enable
DisplayMultiPlaceHold). Check results in staff again.

Remark: A few lines already refer to mandatory note reasons. This is handled
in a subsequent report. No reason to worry.

Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>