fix: add Dialable property to Meeting class

Previously, the meeting class was determining Dialable based on a meeting ID being "0". This is a Zoom-specific thing, but it has recently become a thing for Cisco codecs to have meetings that aren't necessarily dialable. Adding this property to the `Meeting` class allows the specific codec type to set it correctly based on that codec's needs.

essentials-framework/Essentials Devices Common/Essentials Devices Common/Codec/iHasScheduleAwareness.cs

@@ -216,6 +216,10 @@ namespace PepperDash.Essentials.Devices.Common.Codec
                 return joinable;
             }
         }
+
+		[JsonProperty("dialable")]
+		public bool Dialable { get; set; }
+
         //public string ConferenceNumberToDial { get; set; }
         [JsonProperty("conferencePassword")]
         public string ConferencePassword { get; set; }