lang: Port TestAstFunc2 to txtar format

This ports TestAstFunc2 from our home-grown content storage system to
the txtar package. Since a single file can be used to represent the
entire folder hierarchy, this makes it much easier to see and edit
tests.

lang/interpret_test/TestAstFunc2/simple-conditional-scoped-lambda-call-args-ooo.txtar

@@ -0,0 +1,22 @@
+-- main.mcl --
+# out of order
+$funcgen1 = func() {
+	func($b) {
+		"hello" + $b
+	}
+}
+$some_bool = false
+$fn = if $some_bool {
+	$funcgen1()
+} else {
+	$funcgen2()
+}
+$funcgen2 = func() {
+	func($bb) {
+		"world" + $bb
+	}
+}
+$out = $fn("wide")
+test $out {}
+-- OUTPUT --
+Vertex: test[worldwide]