Adds some card unit tests, cleans up some comments (#51434)

* Adds unit tests, some more checks, and improves some comments

* sweep sweep sweep?

* Braindamage

code/modules/unit_tests/_unit_tests.dm

@@ -4,6 +4,7 @@
 #ifdef UNIT_TESTS
 #include "anchored_mobs.dm"
 #include "bespoke_id.dm"
+#include "card_mismatch.dm"
 #include "component_tests.dm"
 #include "plantgrowth_tests.dm"
 #include "reagent_id_typos.dm"

code/modules/unit_tests/card_mismatch.dm

@@ -0,0 +1,7 @@
+/datum/unit_test/card_mismatch
+
+/datum/unit_test/card_mismatch/Run()
+	var/message = checkCardpacks(SStrading_card_game.card_packs)
+	message += checkCardDatums()
+	if(message)
+		Fail(message)