[TS] Fix generation of struct members in object api (#7148)

* Fix C/C++ Create<Type>Direct with sorted vectors

If a struct has a key the vector has to be sorted. To sort the vector
you can't use "const".

* Changes due to code review

* Improve code readability

* Add generate of JSON schema to string to lib

* option indent_step is supported

* Remove unused variables

* Fix break in test

* Fix style to be consistent with rest of the code

* [TS] Fix reserved words as arguments (#6955)

* [TS] Fix generation of reserved words in object api (#7106)

* [TS] Fix generation of object api

* [TS] Fix MakeCamel -> ConvertCase

* [TS] Add test for struct of struct of struct

* Update generated files

* Add missing files

* [TS] Fix query of null/undefined fields in object api

tests/my-game/example/vec3.ts

@@ -130,8 +130,8 @@ pack(builder:flatbuffers.Builder): flatbuffers.Offset {
     this.z,
     this.test1,
     this.test2,
-    (this.test3 === null ? 0 : this.test3.a!),
-    (this.test3 === null ? 0 : this.test3.b!)
+    (this.test3?.a ?? 0),
+    (this.test3?.b ?? 0)
   );
 }
 }