client/tailscale: add Device.PostureIdentity field

New API fields being added in tailscale/corp#15445.

Updates tailscale/corp#15203

Signed-off-by: Paul Scott <paul@tailscale.com>

client/tailscale/devices.go

@@ -71,6 +71,17 @@ type Device struct {
 	AdvertisedRoutes []string `json:"advertisedRoutes"` // Empty for external devices.
 
 	ClientConnectivity *ClientConnectivity `json:"clientConnectivity"`
+
+	// PostureIdentity contains extra identifiers collected from the device when
+	// the tailnet has the device posture identification features enabled. If
+	// Tailscale have attempted to collect this from the device but it has not
+	// opted in, PostureIdentity will have Disabled=true.
+	PostureIdentity *DevicePostureIdentity `json:"postureIdentity"`
+}
+
+type DevicePostureIdentity struct {
+	Disabled      bool     `json:"disabled,omitempty"`
+	SerialNumbers []string `json:"serialNumbers,omitempty"`
 }
 
 // DeviceFieldsOpts determines which fields should be returned in the response.