add tests

assets/tests/ruby/call_script_function_with_params.rb

@@ -0,0 +1,7 @@
+STATE = {
+	"called_with" => nil
+}
+
+def test_func(x)
+  called_with = x
+end

assets/tests/ruby/script_function_gets_called_from_rust_with_multiple_params.rb

@@ -0,0 +1,9 @@
+STATE = {
+	'a_value' => nil,
+	'b_value' => nil
+}
+
+def test_func(a, b)
+  STATE['a_value'] = a
+  STATE['b_value'] = b
+end