Bug 30848: Expand unit tests

Bug 30848: Expand unit tests

Add to the unit tests to test Library and Itemtype expansions as well as
linking multiple subfields of the same marc field to such expansions.

Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
(cherry picked from commit 6b04e3e18f1c534e3d7d91dde458d30e02e13f33)

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
(cherry picked from commit 66999034d4ce274dec14340c1494dc280292984a)
Signed-off-by: Arthur Suzuki <arthur.suzuki@biblibre.com>
(cherry picked from commit 8987b899709e5a8329f0f71b46aae476de83358b)
Signed-off-by: Victor Grousset/tuxayo <victor@tuxayo.net>