* Add test for optional enums in Kotlin
* Rename optional_scalars2.fbs into optional_scalars.fbs
Also updated all references in the project to point to
"optional_scalars.fbs" instead of "optional_scalars2.fbs".
* Moved C++ to optional_scalars2 and added some tests.
Also deleted unused optional_scalars_generated.lobster
* Fixed whitespece in C++ gencode & fixed BUILD file
* Moved C++ onto optional_scalars2 in the .bat file
Co-authored-by: Casper Neo <cneo@google.com>