Fix mediaType not updated after publisher renegotiations

The "mediaTypes" attribute is checked to know if a publisher needs to be
closed when the permissions are updated. However, that attribute was set
only when the publisher was initially created; due to this if a
publisher then used a renegotiation to add media not included in the
original offer the publisher would not be closed if the publishing
permission for that media was later revoked.

Signed-off-by: Daniel Calviño Sánchez <danxuliu@gmail.com>

mcu_common.go

@@ -90,6 +90,7 @@ type McuPublisher interface {
 	McuClient
 
 	HasMedia(MediaType) bool
+	SetMedia(MediaType)
 }
 
 type McuSubscriber interface {