bluez5: allow same codec ID to correspond to multiple endpoints

The codec IDs are user-visible properties.

Some codecs can have multiple endpoints (e.g. different caps struct, or
multiple possible vendor ids), so this detail should not leak to the
user.

spa/plugins/bluez5/a2dp-codecs.h

@@ -350,6 +350,7 @@ struct a2dp_codec {
 
 	const char *name;
 	const char *description;
+	const char *endpoint_name;	/**< Endpoint name. If NULL, same as name */
 	const struct spa_dict *info;
 
 	const size_t send_buf_size;