Summary:
This provides various versions of SampleTurboModule, that are:
* compatible with existing NativeModule
* TurboModule compliant
Variants:
* RCTSampleTurboModule (traditional objc module)
* RCTSampleTurboCxxModule (objc++ module using CxxModule)
* SampleTurboModule (pure C++ impl of a TurboModule, no ObjC)
As noted in some files, they need to be codegen'ed based on the `NativeSampleTurboModule.js` (Flow type). The codegen script is not yet usable in OSS (we'll work on it some time in H2 2019). For now, these files need to be manually synced with Flow type.
Reviewed By: cpojer
Differential Revision: D14932539
fbshipit-source-id: fb887192384e5e6e4dff4cac68b4e037a4783cd9