Update ts codegen (#8421)

Makes the return type of `static getFullyQualifiedName()` be a string literal instead of just the string type

Update tests

Co-authored-by: Björn Harrtell <bjornharrtell@users.noreply.github.com>

tests/ts/my-game/example/test-simple-table-with-enum.ts

@@ -41,7 +41,7 @@ mutate_color(value:Color):boolean {
   return true;
 }
 
-static getFullyQualifiedName():string {
+static getFullyQualifiedName(): "MyGame.Example.TestSimpleTableWithEnum" {
   return 'MyGame.Example.TestSimpleTableWithEnum';
 }