Add examples of icons on tools, resources, prompts, and server implementation to EverythingServer (#1096)

Co-authored-by: Stephen Halter <halter73@gmail.com>

samples/EverythingServer/Tools/AddTool.cs

@@ -6,6 +6,6 @@ namespace EverythingServer.Tools;
 [McpServerToolType]
 public class AddTool
 {
-    [McpServerTool(Name = "add"), Description("Adds two numbers.")]
+    [McpServerTool(Name = "add", IconSource = "https://raw.githubusercontent.com/microsoft/fluentui-emoji/62ecdc0d7ca5c6df32148c169556bc8d3782fca4/assets/Plus/Flat/plus_flat.svg"), Description("Adds two numbers.")]
     public static string Add(int a, int b) => $"The sum of {a} and {b} is {a + b}";
 }