Bug 10267: Show error message if user tries to enter too many characters for cardnumber

Bug 10267: Show error message if user tries to enter too many characters for cardnumber

This patch displays a message if the user tries to enter more than the
max number of characters for a cardnumber.

To test:
1) Apply patch and go to Patrons -> New patron
2) Scroll down to Card number
3) Put in any characters. Notice that when you have entered the max
number of characters, you are unable to type any more.
4) Click out of the text field (so it loses focus), the error message will show up.
5) if you backspace some characters and click out of the text field
again, the message should disappear

Sponsored-by: Catalyst IT

Followed test plan, works as expected
Signed-off-by: Marc Véron <veron@veron.ch>

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>

Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>