Bug 21898: Add aqbasket to available tables for ACQORDER

Bug 21898: Add aqbasket to available tables for ACQORDER

This patch should allow <<aqbasket.$field>> replacements to work in both
email subject and email content fields for notices.

Test plan
1/ Add <<aqbasket.basketname>> into the ACQORDER notice (In the subject
line and content box)
2/ Trigger said notice to send (before applying the patch)
3/ Note that the replacements have not taken place..
<<aqbasket.basketname>> is present as is.
4/ Apply patch
5/ Trigger the notice again
6/ Note that the replacements are now made.
7/ Signoff

Signed-off-by: Séverine QUEUNE <severine.queune@bulac.fr>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
JD amended patch: fix alignment in hashref, edit commit message to fix
letter code "AQORDER" vs "ACQORDER"

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