Changes

Bug #14753

In the MyLinks personal tool, ensure the name and the description of
each link are correctly encoded for HTML.

Bug #14806

Add FieldValueTemplate to model the template of a field value in a
RecordTemplate of a form. This is to avoid to parse template parameters
for both keys and values of fields in a FieldTemplate; the way they are
encoded in the FieldTemplate has to be encapsulated and not exposed.

Bug #14753

In Kmelia, fix bug by removing the encoding of the description for HTML
but ensure it is well encoded for Js to avoid any attack by using
js/HTML code injected in the description

Bug #14806

Fix the bug:
- Now the form used to create subscription is decoupled from the search
  form used to search and filter classifieds. It is generated directly
  from the two fields to use for search and for subscription.
- Only one value is selectable for each field used for subscription: so
  they are selectable through a selection list.
- When a field isn't valued for a subscription, set its value to an
  empty String.

Remove duplication code by providing reusable method in parent classes
(the ClassifiedValidationHandler abstract class has been added for this
purpose).

Add two new classes, SubscriptionField and SubscriptionFieldValue to
model the two fields and their selectable values used in the
subscription. They are used to generate the HTML form for subscription.