Bug 35398: Unit test

Bug 35398: Unit test

This patch adds the begginings of unit tests for Koha::EDI.  Right now
we only test that a simple QUOTE message creates a basket, adds the item
to said basket and assigns that single item to a corresponding stock
rotation rota as defined by the LRP segment in the QUOTE message.

It lays the foundations for much more rigorous tests to be written to
cover the whole of EDI.pm however.

Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>
(cherry picked from commit de79e957ce82d53d9978551f1d7ef593884daa29)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>