Add api to get device id

src/device.js

@@ -183,6 +183,26 @@ class Device extends DeviceBase {
 		return r.serial;
 	}
 
+	/**
+	 * Get the device's id.
+	 *
+	 * Supported platforms:
+	 * - Gen 3 (since Device OS 0.9.0)
+	 * - Gen 2 (since Device OS 1.5.0)
+	 *
+	 * @param {Object} [options] Options.
+	 * @param {Number} [options.timeout] Timeout (milliseconds).
+	 * @return {Promise<String>}
+	 */
+	async getDeviceId({ timeout = globalOptions.requestTimeout } = {}) {
+		const r = await this.sendProtobufRequest(
+			'GetDeviceIdRequest',
+			null,
+			{ timeout }
+		);
+		return r.id;
+	}
+
 	/**
 	 * Perform the system reset.
 	 *

src/device.test.js

@@ -30,6 +30,14 @@ describe('Device', () => {
 		expect(result).to.eql(exampleSerialNumber);
 	});
 
+	it('provides getDeviceId()', async () => {
+		const exampleDeviceId = '0123456789abcdef';
+		sinon.stub(device, 'sendProtobufRequest').resolves({ id: exampleDeviceId });
+		const result = await device.getDeviceId();
+		expect(device.sendProtobufRequest).to.have.property('callCount', 1);
+		expect(result).to.eql(exampleDeviceId);
+	});
+
 	it('provides enterListeningMode()', async () => {
 		sinon.stub(device, 'sendProtobufRequest');
 		device.sendProtobufRequest.onCall(0).resolves({});

src/request.js

@@ -2,6 +2,11 @@ const { definitions: proto } = require('@particle/device-os-protobuf');
 
 // Mapping of request types to Protobuf messages
 const Request = {
+	GET_DEVICE_ID: {
+		id: 20,
+		request: proto.GetDeviceIdRequest,
+		reply: proto.GetDeviceIdReply
+	},
 	GET_SERIAL_NUMBER: {
 		id: 21,
 		request: proto.GetSerialNumberRequest,