add recovery_refresh app and api and use it in mod_conference to send a message to the channel telling it to sync its recovery snapshot

src/include/switch_types.h

@@ -791,6 +791,7 @@ typedef enum {
 	SWITCH_MESSAGE_INDICATE_UDPTL_MODE,
 	SWITCH_MESSAGE_INDICATE_CLEAR_PROGRESS,
 	SWITCH_MESSAGE_INDICATE_JITTER_BUFFER,
+	SWITCH_MESSAGE_INDICATE_RECOVERY_REFRESH,
 	SWITCH_MESSAGE_INVALID
 } switch_core_session_message_types_t;