[TypeScript] Fix namespaceless schema generation (#7432)

* Add tests for ts flatc

* fix typescript generation of namespaceless file

* Add typescript genereated code from generate_code.py

* Support multiple module flatc testing

tests/flatc/foo_with_ns.fbs

@@ -0,0 +1,9 @@
+include "bar/bar.fbs";
+
+namespace something;
+
+table Foo {
+  bar:Bar;
+}
+
+root_type Foo;