vendor: move vendored sources in-tree

This should make it easier to see changes instead of just a blob

vendor/github.com/rabbitmq/amqp091-go/fuzz.go

@@ -0,0 +1,23 @@
+// Copyright (c) 2021 VMware, Inc. or its affiliates. All Rights Reserved.
+// Copyright (c) 2012-2021, Sean Treadway, SoundCloud Ltd.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build gofuzz
+// +build gofuzz
+
+package amqp091
+
+import "bytes"
+
+func Fuzz(data []byte) int {
+	r := reader{bytes.NewReader(data)}
+	frame, err := r.ReadFrame()
+	if err != nil {
+		if frame != nil {
+			panic("frame is not nil")
+		}
+		return 0
+	}
+	return 1
+}