CMake: Place all built files in a single folder in MSVC

This PR makes builds all the project outputs (citra-qt.exe, citra.exe and their corresponding extra files) to BUILD_DIR/bin/<Configuration> when compiling with MSVC, it provides a single place where to find these files for each configuration without having to dig through the src folder to find them.

This PR will also help with the cmake modifications I'm working on to automatically copy the Qt libraries when working with MSVC.