Bug 17965: TT syntax for notices - Prove that DUEDGST is compatible

Bug 17965: TT syntax for notices - Prove that DUEDGST is compatible

This notice template have the particular feature of using <<count>>.
This value is substitued during the process of the notice template.
For the TT syntax, all what we need is to send the values to substitute to the
template.

Note that items.content can also be used in these template, you can have
a look at bug 17967 to see a better alternative to this marker.

Test plan:
Generate DUEDGST and DUE notice messages.
You should be able to generate the same messages with the TT syntax.

Signed-off-by: Marc Véron <veron@veron.ch>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>