lang: Allow a list of strings in the resource name

This adds a core looping construct by allowing a list of names to build
a resource. They'll all have the same parameters, but they'll
intelligently add the correct list of edges that they'd individually
create.

Constructs like these are one reason we do NOT have actual looping
functionality in the language, and it should stay that way.

lang/interpret_test/TestAstFunc1/empty-res-list-0/main.mcl

@@ -0,0 +1,13 @@
+# this is an empty list of test resources, iow test resources
+# this must pass type unification
+test [] {}
+
+# single resource
+test "name" {}
+
+# single resource, defined by list variable
+$names = ["hey",]
+test $names {}
+
+# multiples resources, defined by list
+test ["hello", "world",] {}