ARI: Add the ability to subscribe to all events

This patch adds the ability to subscribe to all events. There are two possible
ways to accomplish this:
(1) On initial WebSocket connection. This patch adds a new query parameter,
    'subscribeAll'. If present and True, Asterisk will subscribe the
    applications to all ARI events.
(2) Via the applications resource. When subscribing in this manner, an ARI
    client should merely specify a blank resource name, i.e., 'channels:'
    instead of 'channels:12354'. This will subscribe the application to all
    resources of the 'channels' type.

ASTERISK-24870 #close

Change-Id: I4a943b4db24442cf28bc64b24bfd541249790ad6

rest-api/api-docs/events.json

@@ -26,6 +26,14 @@
 							"required": true,
 							"allowMultiple": true,
 							"dataType": "string"
+						},
+						{
+							"name": "subscribeAll",
+							"description": "Subscribe to all Asterisk events. If provided, the applications listed will be subscribed to all events, effectively disabling the application specific subscriptions. Default is 'false'.",
+							"paramType": "query",
+							"required": false,
+							"allowMultiple": false,
+							"dataType": "boolean"
 						}
 					]
 				}