res_pjsip_mwi: Set up unsolicited MWI upon registration.

The res_pjsip_mwi previously required a reload to set up the proper
subscriptions to allow unsolicited MWI to work. This change
makes it so the act of registering will also cause this to occur.
This is particularly useful if realtime is involved as no reload
needs to occur within Asterisk to cause the MWI information
to get sent.

ASTERISK-25180 #close

Change-Id: Id847b47de4b8b3ab8858455ccc2f07b0f915f252

include/asterisk/res_pjsip.h

@@ -168,6 +168,8 @@ struct ast_sip_contact {
 	int authenticate_qualify;
 	/*! Qualify timeout. 0 is diabled. */
 	double qualify_timeout;
+	/*! Endpoint that added the contact, only available in observers */
+	struct ast_sip_endpoint *endpoint;
 };
 
 #define CONTACT_STATUS "contact_status"
@@ -962,12 +964,14 @@ struct ast_sip_contact *ast_sip_location_retrieve_contact(const char *contact_na
  * \param expiration_time Optional expiration time of the contact
  * \param path_info Path information
  * \param user_agent User-Agent header from REGISTER request
+ * \param endpoint The endpoint that resulted in the contact being added
  *
  * \retval -1 failure
  * \retval 0 success
  */
 int ast_sip_location_add_contact(struct ast_sip_aor *aor, const char *uri,
-	struct timeval expiration_time, const char *path_info, const char *user_agent);
+	struct timeval expiration_time, const char *path_info, const char *user_agent,
+	struct ast_sip_endpoint *endpoint);
 
 /*!
  * \brief Update a contact