types/persist: add AttestationKey (#17281)

Extend Persist with AttestationKey to record a hardware-backed
attestation key for the node's identity.

Add a flag to tailscaled to allow users to control the use of
hardware-backed keys to bind node identity to individual machines.

Updates tailscale/corp#31269


Change-Id: Idcf40d730a448d85f07f1bebf387f086d4c58be3

Signed-off-by: Patrick O'Doherty <patrick@tailscale.com>

cmd/cloner/clonerex/clonerex.go

@@ -1,7 +1,7 @@
 // Copyright (c) Tailscale Inc & AUTHORS
 // SPDX-License-Identifier: BSD-3-Clause
 
-//go:generate go run tailscale.com/cmd/cloner  -clonefunc=true -type SliceContainer
+//go:generate go run tailscale.com/cmd/cloner  -clonefunc=true -type SliceContainer,InterfaceContainer
 
 // Package clonerex is an example package for the cloner tool.
 package clonerex
@@ -9,3 +9,26 @@ package clonerex
 type SliceContainer struct {
 	Slice []*int
 }
+
+// Cloneable is an interface with a Clone method.
+type Cloneable interface {
+	Clone() Cloneable
+}
+
+// CloneableImpl is a concrete type that implements Cloneable.
+type CloneableImpl struct {
+	Value int
+}
+
+func (c *CloneableImpl) Clone() Cloneable {
+	if c == nil {
+		return nil
+	}
+	return &CloneableImpl{Value: c.Value}
+}
+
+// InterfaceContainer has a pointer to an interface field, which tests
+// the special handling for interface types in the cloner.
+type InterfaceContainer struct {
+	Interface Cloneable
+}