Eliminate RSocketRequester usage in RSRequester
Eliminate RSocketRequester usage in RSRequester

Summary:
Update TakeFirst class such that it can be used in StateMachine->requestStream(takeFirst) call.
This makes RSRequester to don't need RSocketRequester, so one less dependency.

In the next diff, it will help us get rid of RSRequester too and make RSocketClientChannel to directly use RSocketStateMachine. Another dependency will be gotten rid of.

Reviewed By: alexmalyshev

Differential Revision: D7981208

fbshipit-source-id: b7b4f5d0d25727ed81ab8512f9c68bdd8dd53207

rsocket/rsocket-cpp,rsocket/rsocket-cpp,ReactiveSocket/reactivesocket-cpp,ReactiveSocket/reactivesocket-cpp,phoad/rsocket-cpp,phoad/rsocket-cpp,phoad/rsocket-cpp,rsocket/rsocket-cpp,rsocket/rsocket-cpp,phoad/rsocket-cpp,ReactiveSocket/reactivesocket-cpp,phoad/rsocket-cpp