Summary:
Similar to https://github.com/facebook/jest/pull/2877, this introduces an optional config `HasteImpl` of type `{getHasteName(filePath: string): (string|void)}` that returns the haste name for a module at filePath if it is a haste module or undefined otherwise.
This allows us to inject a custom implementation of haste's module id resolution rather than only relying on `providesModule` annotations
Reviewed By: davidaurelio
Differential Revision: D4589372
fbshipit-source-id: 4d1983dfbf09c9d67faf725e86ae86ab42433b7d