Bug 24519: Match paycollect form validation for change collection

Bug 24519: Match paycollect form validation for change collection

This patch adds form validation to the Point Of Sale payment page such
that one cannot submit the form with a 'collected' value that is less
than the 'owed' amount.

Signed-off-by: Sally <sally.healey@cheshiresharedservices.gov.uk>
Signed-off-by: Josef Moravec <josef.moravec@gmail.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
(cherry picked from commit 080288bce48cf4fa94b19d35a117dd3e1967a4c9)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>