Added nullability declarations for video encoder callback
Added nullability declarations for video encoder callback

APCVSRepo/sdl_ios,FordDev/sdl_ios,APCVSRepo/sdl_ios,kshala-ford/sdl_ios,FordDev/sdl_ios,smartdevicelink/sdl_ios,FordDev/sdl_ios,smartdevicelink/sdl_ios,kshala-ford/sdl_ios,smartdevicelink/sdl_ios,APCVSRepo/sdl_ios,FordDev/sdl_ios,smartdevicelink/sdl_ios,kshala-ford/sdl_ios,APCVSRepo/sdl_ios,smartdevicelink/sdl_ios,FordDev/sdl_ios,kshala-ford/sdl_ios,APCVSRepo/sdl_ios,kshala-ford/sdl_ios