[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/union_vector/union_vector_generated.ts

@@ -0,0 +1,8 @@
+export { Attacker, AttackerT } from './attacker';
+export { BookReader, BookReaderT } from './book-reader';
+export { Character, unionToCharacter, unionListToCharacter } from './character';
+export { FallingTub, FallingTubT } from './falling-tub';
+export { Gadget, unionToGadget, unionListToGadget } from './gadget';
+export { HandFan, HandFanT } from './hand-fan';
+export { Movie, MovieT } from './movie';
+export { Rapunzel, RapunzelT } from './rapunzel';