Summary:
Our long-term plan is to completely illuminate `jsi::Value`-to-`folly::dynamic` serialization step in prop parsing process improving performance and memory pressure. At the same time, we don't want to introduce a hard dependency in application code to JSI because it exposes direct access to VM and prevents parsing some data that come *NOT* from JSVM.
RawValue is an extremely light-weight (hopefully fully optimized-out) abstraction that provides limited JSON-like and C++-idiomatic interface.
The current particular implementation is still using `folly::dynamic` inside, but I have fully JSI-powered one which will replace the current one right after we figure out how to deal with folly::dynamic-specific callsites. Or we can implement RawValue in a hybrid manner if a code-size implication of that will be minimal.
Reviewed By: JoshuaGross, mdvacca
Differential Revision: D13962466
fbshipit-source-id: e848522fd242f21e9e771773f2103f1c1d9d7f21