Reorganize tests and benchmark scripts.

Mainly to get rid of one top level directory. But this will
also be useful when there are tests of the embedding API.

test/language/inheritance/do_not_inherit_static_methods.wren

@@ -0,0 +1,7 @@
+class Foo {
+  static methodOnFoo { IO.print("foo") }
+}
+
+class Bar is Foo {}
+
+Bar.methodOnFoo // expect runtime error: Bar metaclass does not implement 'methodOnFoo'.