This allows to use DLLOVERRIDES with native DLLs, making it more convenient for testing and debugging. This will also makes it possible to create an alternative media source implementation with a different backend without breaking the current one.
-- v2: mfmp4srcsnk: Register the MP3 and MPEG4 sink factory classes. mfasfsrcsnk: Register the Asf Byte Stream Handler class. mfmp4srcsnk: Register the MPEG4 Byte Stream Handler class. mfsrcsnk: Register the WAV Byte Stream Handler class. mfsrcsnk: Register the AVI Byte Stream Handler class. mfsrcsnk: Refactor sink class factory helpers.