[MIRROR] Unit Tests Door/Airlock Access Working [MDB IGNORE] (#18568)

* Unit Tests Door/Airlock Access Working (#72461)

I screwed up with my access changes (on my local, I made sure I could
still open doors rather than be kept out of places), and #72458 fixes
that. However, let's also add a unit test to prevent that regression
again. We just do five different access "checks", and see if all five
different scenarios should work as intended.

As you can see, this PR will not pass unit tests. This is supposed to
happen, because at the time of this PR is opened, we will be in a
regression state that the aforementioned PR fixes. When the
aforementioned PR is merged, it should clear CI without any difficulties
(I know this because I ran the unit test myself)

* Unit Tests Door/Airlock Access Working

Co-authored-by: san7890 <the@san7890.com>

code/modules/unit_tests/_unit_tests.dm

@@ -104,6 +104,7 @@
 #include "create_and_destroy.dm"
 #include "dcs_get_id_from_elements.dm"
 #include "designs.dm"
+#include "door_access.dm"
 #include "dragon_expiration.dm"
 #include "drink_icons.dm"
 #include "dummy_spawn.dm"