Adding AddEventListener to DesktopAgent and Channels

Author: kemerava

docs/api/ref/DesktopAgent.md

@@ -90,6 +90,9 @@ interface IDesktopAgent
     Task<IPrivateChannel> CreatePrivateChannel();
     Task<IEnumerable<IChannel>> GetUserChannels();
 
+    // non-context events
+    Task<IListener> AddEventListener(string? eventType, Fdc3EventHandler handler);
+
     // OPTIONAL channel management functions
     Task JoinUserChannel(string channelId);
     Task<IChannel?> GetCurrentChannel();
@@ -189,8 +192,8 @@ addEventListener(type: FDC3EventTypes  | null, handler: EventHandler): Promise<L
 </TabItem>
 <TabItem value="dotnet" label=".NET">
 
-```
-Not implemented
+```csharp
+Task<IListener> AddEventListener(string? eventType, Fdc3EventHandler handler);
 ```
 
 </TabItem>
@@ -210,16 +213,20 @@ Whenever the handler function is called it will be passed an event object with d
 const listener = await fdc3.addEventListener(null, event => { ... });
 
 // listener for a specific event type that logs its details
-const userChannelChangedListener = await fdc3.addEventListener("userChannelChanged ", event => { 
+const userChannelChangedListener = await fdc3.addEventListener("userChannelChanged", event => { 
   console.log(`Received event ${event.type}\n\tDetails: ${event.details}`);
   //do something else with the event
 });
 ```
 </TabItem>
 <TabItem value="dotnet" label=".NET">
 
-```
-Not implemented
+```csharp
+var listener = await _desktopAgent.AddEventListener(null, (event) => { ... });
+
+var userChannelChangedListener = await _desktopAgent.AddEventListener("userChannelChanged", (event) => {
+  System.Diagnostics.Debug.Write($"Received event ${event.Type}\n\tDetails: ${event.Details}");
+});
 ```
 
 </TabItem>

docs/api/ref/PrivateChannel.md

@@ -40,6 +40,10 @@ interface  PrivateChannel extends Channel {
 ```csharp
 interface IPrivateChannel : IChannel, IIntentResult
 {
+    //functions
+    Task<IListener> AddEventListener(string? eventType, Fdc3EventHandler handler);
+
+    //deprecated functions
     IListener OnAddContextListener(Action<string?> handler);
     IListener OnUnsubscribe(Action<string?> handler);
     IListener OnDisconnect(Action handler);
@@ -233,7 +237,7 @@ addEventListener(type: PrivateChannelEventTypes  | null, handler: EventHandler):
 <TabItem value="dotnet" label=".NET">
 
 ```csharp
-Not implemented
+Task<IListener> AddEventListener(string? eventType, Fdc3EventHandler handler);
 ```
 
 </TabItem>
@@ -257,7 +261,10 @@ const listener: Listener = await myPrivateChannel.addEventListener(null,
 <TabItem value="dotnet" label=".NET">
 
 ```csharp
-Not implemented
+IChannel myPrivateChannel;
+var listener = await myPrivateChannel.AddEventListener(null, (event) => {
+    System.Diagnostics.Debug.WriteLine($"Received event ${event.Type}\n\tDetails: ${event.Details}");
+});
 ```
 
 </TabItem>