Move InPlaceConstruction test in folly/test/SynchronizedTest.cpp
Move InPlaceConstruction test in folly/test/SynchronizedTest.cpp

Summary: [Folly] Move `InPlaceConstruction` test in `folly/test/SynchronizedTest.cpp`.

Differential Revision: D6653481

fbshipit-source-id: f0eadfd6c2f41e9f597a666d01e40d5553447c70

facebook/folly,rklabs/folly,facebook/folly,facebook/folly,rklabs/folly,facebook/folly,rklabs/folly,rklabs/folly,facebook/folly,rklabs/folly