FS-7500: add support for codec control and use it to pass messages down to the codec and use it to implement keyframe reset for fir, pli and nack. Later we will expand to handle nack correctly.

src/include/switch_module_interfaces.h

@@ -679,6 +679,8 @@ struct switch_codec_implementation {
 	switch_core_codec_video_encode_func_t encode_video;
 	/*! function to decode video encoded data into raw data */
 	switch_core_codec_video_decode_func_t decode_video;
+	/*! function to send control messages to the codec */
+	switch_core_codec_control_func_t codec_control;
 	/*! deinitalize a codec handle using this implementation */
 	switch_core_codec_destroy_func_t destroy;
 	uint32_t codec_id;