Summary:
TextInput now acts as a host component and can be passed directly to our new APIs that require a host component. Callsites no longer need to call
```
inputRef.getNativeRef()
```
We mutate the ref to the host component adding the imperative methods of the TextInput so you can still call `inputRef.clear` and `inputRef.isFocused`.
Changelog:
[General][Changed] TextInput now uses `forwardRef` allowing it to be used directly by new APIs requiring a host component.
Reviewed By: yungsters
Differential Revision: D18458408
fbshipit-source-id: 1f149fd575210d702fa0fdf3d05bb2162436a773
Eli White
bbc5c35a61