mcp/examples: moves middleware examples into example folder (modelcontextprotocol#356)

For better organization.

Author: samthanawalla

mcp/example_progress_test.go renamed to examples/client/middleware/main.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by an MIT-style
 // license that can be found in the LICENSE file.
 
-package mcp_test
+package main
 
 import (
 	"context"
@@ -15,10 +15,9 @@ var nextProgressToken atomic.Int64
 
 // This middleware function adds a progress token to every outgoing request
 // from the client.
-func Example_progressMiddleware() {
-	c := mcp.NewClient(testImpl, nil)
+func main() {
+	c := mcp.NewClient(&mcp.Implementation{Name: "test"}, nil)
 	c.AddSendingMiddleware(addProgressToken[*mcp.ClientSession])
-	_ = c
 }
 
 func addProgressToken[S mcp.Session](h mcp.MethodHandler) mcp.MethodHandler {

mcp/example_middleware_test.go renamed to examples/server/middleware/main.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by an MIT-style
 // license that can be found in the LICENSE file.
 
-package mcp_test
+package main
 
 import (
 	"context"
@@ -16,7 +16,7 @@ import (
 )
 
 // This example demonstrates server side logging using the mcp.Middleware system.
-func Example_loggingMiddleware() {
+func main() {
 	// Create a logger for demonstration purposes.
 	logger := slog.New(slog.NewTextHandler(os.Stdout, &slog.HandlerOptions{
 		Level: slog.LevelInfo,