MMDevice: Deprecate functions

[marktsuchida]

• Those discussed in Investigate and maybe remove "Autofocus support" in CoreCallback #295
• Get/SetModuleHandle(), which were deprecated in comment
• Direct access to device pointers, deprecated in comment

Of these, here are the functions currently used by device adapters on Windows:

DeviceAdapters\FakeCamera\FakeCamera.cpp(461,25): warning C4996: 'MM::Core::GetFocusPosition': was declared deprecated
DeviceAdapters\TwoPhoton\VirtualShutter.cpp(124,46): warning C4996: 'MM::Core::GetSignalIODevice': was declared deprecated
DeviceAdapters\TwoPhoton\VirtualShutter.cpp(132,46): warning C4996: 'MM::Core::GetSignalIODevice': was declared deprecated
DeviceAdapters\TwoPhoton\VirtualShutter.cpp(153,46): warning C4996: 'MM::Core::GetSignalIODevice': was declared deprecated
DeviceAdapters\TwoPhoton\VirtualShutter.cpp(168,46): warning C4996: 'MM::Core::GetSignalIODevice': was declared deprecated

(It's good to deprecate these to warn against future use even if we end up keeping the used functions for some time.)