Summary:
Following our internal discussion we want to change previously used name convention.
Now it looks like:
```
#import <FBReactNativeTestSpec/FBReactNativeTestSpec.h>
```
Name is a param of `rn_codegen` and `rn_library`. Also, I found it the easiest to move replacing `::_IMPORT_::` into buck rule
Reviewed By: fkgozali
Differential Revision: D16646616
fbshipit-source-id: 2c33c5b4d1c42b0e6f5a42d9a318bd8bda9745f4
Summary: Cpp and Objcpp should not be in the same rules since codegen has different purposes. I split them into into two rules and update tests for new names.
Reviewed By: TheSavior
Differential Revision: D16599257
fbshipit-source-id: 3a8be8c0e289825f9d5db831cc2eec3d2bf9728d
Summary: Add a test to ensure that the generated code is syntactically valid and compiles.
Reviewed By: JoshuaGross, osdnk
Differential Revision: D16518542
fbshipit-source-id: d4fadaeb29194ca38c8a99874ab304a464632894
Andres Suarez
Michał Osadnik
Eli White