manager: Set AMI event "Newexten" to the EVENT_FLAG_DIALPLAN class

The documentation already specified EVENT_FLAG_DIALPLAN for this
event, but the implementation was using EVENT_FLAG_CALL.

Using EVENT_FLAG_DIALPLAN allows AMI clients to opt out of receiving
this highly verbose event.

ASTERISK-28033

Change-Id: I45b3119f30e4dbc17b49831f2b1a4f2c1beadafe

CHANGES

@@ -64,6 +64,10 @@ AMI
    and ContactStatusDetail are now set to "NonQualified" when a contact exists
    but has not been qualified.
 
+ * The "Newexten" event is now part of the "dialplan" class. The documentation
+   for Asterisk 15 already specified this, but the implementation was actually
+   using the "call" class instead.
+
 ARI
 ------------------
  * The ContactInfo event's contact_status field is now set to "NonQualified"

UPGRADE-16.txt

@@ -41,6 +41,9 @@ AMI:
    but has not been qualified.
  - The ContactStatus event will no longer be sent by PJSIP when a device
    refreshes its registration.
+ - The "Newexten" event is now part of the "dialplan" class. The documentation
+   for Asterisk 15 already specified this, but the implementation was actually
+   using the "call" class instead.
 
 ARI:
  - The ContactInfo event's contact_status field is now set to "NonQualified"

main/manager_channels.c

@@ -638,7 +638,7 @@ static struct ast_manager_event_blob *channel_newexten(
 
 	/* DEPRECATED: Extension field deprecated in 12; remove in 14 */
 	return ast_manager_event_blob_create(
-		EVENT_FLAG_CALL, "Newexten",
+		EVENT_FLAG_DIALPLAN, "Newexten",
 		"Extension: %s\r\n"
 		"Application: %s\r\n"
 		"AppData: %s\r\n",