Summary:
Adds C++ delta client that keeps modules in memory, and can be used as a RAM bundle.
For now, this client expects a `folly::dynamic` object as payload for patches, i.e. the JSON response retrieved from Metro needs to be parsed with `folly::parseJson` by the caller.
In the future, we will replace JSON with a streaming friendly binary format.
Reviewed By: fromcelticpark
Differential Revision: D7845136
fbshipit-source-id: f003f98a2607c8354c427a7e60e01e19e20295b1
David Aurelio