Add CLI DevTunnel sanity test (#291813)

* Add CLI -> DevTunnel -> Web tests

* PR feedback

test/sanity/src/githubAuth.ts

@@ -0,0 +1,36 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import { Browser, Page } from 'playwright';
+import { TestContext } from './context.js';
+
+/**
+ * Handles GitHub authentication flows in the browser.
+ */
+export class GitHubAuth {
+	// private readonly username = process.env.GITHUB_ACCOUNT;
+	// private readonly password = process.env.GITHUB_PASSWORD;
+
+	public constructor(private readonly context: TestContext) { }
+
+	/**
+	 * Runs GitHub device authentication flow in a browser.
+	 * @param browser Browser to use.
+	 * @param code Device authentication code to use.
+	 */
+	public async runDeviceCodeFlow(browser: Browser, code: string) {
+		this.context.log(`Running GitHub device flow with code ${code}`);
+		const page = await browser.newPage();
+		await page.goto('https://github.com/login/device');
+	}
+
+	/**
+	 * Runs GitHub user authentication flow in the browser.
+	 * @param page Authentication page.
+	 */
+	public async runUserWebFlow(page: Page) {
+		this.context.log(`Running GitHub browser flow at ${page.url()}`);
+	}
+}