Update contextId for close browser utility.

Author: Visagan Guruparan

src/Plugins/BotSharp.Plugin.WebDriver/UtilFunctions/UtilWebCloseBrowserFn.cs

@@ -28,7 +28,7 @@ public async Task<bool> Execute(RoleDialogModel message)
             ContextId = webDriverService.GetMessageContext(message)
         };
 
-        await browser.CloseBrowser(message.CurrentAgentId);
+        await browser.CloseBrowser(msg.ContextId);
 
         message.Content = $"Browser closed.";