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/cloner_test.go

@@ -59,3 +59,52 @@ func TestSliceContainer(t *testing.T) {
 		})
 	}
 }
+
+func TestInterfaceContainer(t *testing.T) {
+	examples := []struct {
+		name string
+		in   *clonerex.InterfaceContainer
+	}{
+		{
+			name: "nil",
+			in:   nil,
+		},
+		{
+			name: "zero",
+			in:   &clonerex.InterfaceContainer{},
+		},
+		{
+			name: "with_interface",
+			in: &clonerex.InterfaceContainer{
+				Interface: &clonerex.CloneableImpl{Value: 42},
+			},
+		},
+		{
+			name: "with_nil_interface",
+			in: &clonerex.InterfaceContainer{
+				Interface: nil,
+			},
+		},
+	}
+
+	for _, ex := range examples {
+		t.Run(ex.name, func(t *testing.T) {
+			out := ex.in.Clone()
+			if !reflect.DeepEqual(ex.in, out) {
+				t.Errorf("Clone() = %v, want %v", out, ex.in)
+			}
+
+			// Verify no aliasing: modifying the clone should not affect the original
+			if ex.in != nil && ex.in.Interface != nil {
+				if impl, ok := out.Interface.(*clonerex.CloneableImpl); ok {
+					impl.Value = 999
+					if origImpl, ok := ex.in.Interface.(*clonerex.CloneableImpl); ok {
+						if origImpl.Value == 999 {
+							t.Errorf("Clone() aliased memory with original")
+						}
+					}
+				}
+			}
+		})
+	}
+}