go: include vendored modules

RHEL requires the source code for dependencies to be included in the
srpm. The spec file already expects that, but we've only included the
vendored modules (i.e., the `vendor` directory) in the `rhel-8.2.`
branch. Move vendoring to master, so that we can build RHEL packages
from it as well.

This commit is the result of running `go mod vendor`, which includes the
vendored sources and updates go.mod and go.sum files.

Fedora requires the opposite: dependencies should not be vendored. The
spec file already ignores the `vendor` directory by default.

vendor/github.com/google/uuid/marshal.go

@@ -0,0 +1,37 @@
+// Copyright 2016 Google Inc.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package uuid
+
+import "fmt"
+
+// MarshalText implements encoding.TextMarshaler.
+func (uuid UUID) MarshalText() ([]byte, error) {
+	var js [36]byte
+	encodeHex(js[:], uuid)
+	return js[:], nil
+}
+
+// UnmarshalText implements encoding.TextUnmarshaler.
+func (uuid *UUID) UnmarshalText(data []byte) error {
+	id, err := ParseBytes(data)
+	if err == nil {
+		*uuid = id
+	}
+	return err
+}
+
+// MarshalBinary implements encoding.BinaryMarshaler.
+func (uuid UUID) MarshalBinary() ([]byte, error) {
+	return uuid[:], nil
+}
+
+// UnmarshalBinary implements encoding.BinaryUnmarshaler.
+func (uuid *UUID) UnmarshalBinary(data []byte) error {
+	if len(data) != 16 {
+		return fmt.Errorf("invalid UUID (got %d bytes)", len(data))
+	}
+	copy(uuid[:], data)
+	return nil
+}