test(loot): item source keys and the quickbuild item cost's source

Covers the key names and name value types, a pickup from an object, from the
player and from an object that is gone, metrics after an item's config (and
not kept on the item), a removal's loot source, and a quickbuild taking its
item cost with itself as the source.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/dGameTests/dComponentsTests/CMakeLists.txt

@@ -19,6 +19,7 @@ set(DCOMPONENTS_TESTS
 	"ReplicaConstructionTests.cpp"
 	"ReplicaDecoderTests.cpp"
 	"ItemRemovalTests.cpp"
+	"LootMetricsTests.cpp"
 )
 
 # Get the folder name and prepend it to the files above