feat(e2e): add support running behind proxy (#5348)

* docs: update maintaining

* chore(e2e): add maxFailures to playwright

* fix(ci): skip submodule in e2e job

We don't need the submodules for the e2e job. This will speed up the
checkout step.

* feat(ci): add test-e2e-proxy job

This adds a new job to CI to run our tests behind Caddy and simulate
code-server running against a reverse-proxy.

* refactor: make e2e work with reverse proxy

This refactors the e2e test in a couple ways:
- remove setting cookie in localStorage (instead we pass --auth none)
- refactor address() method to account for reverse proxy logic

* Update test/e2e/models/CodeServer.ts

* Update test/playwright.config.ts

* Update test/utils/constants.ts

Co-authored-by: Asher <ash@coder.com>

* Update test/utils/helpers.ts

Co-authored-by: Asher <ash@coder.com>

Co-authored-by: Asher <ash@coder.com>

test/e2e/openHelpAbout.test.ts

@@ -1,7 +1,7 @@
 import { version } from "../../src/node/constants"
 import { describe, test, expect } from "./baseFixture"
 
-describe("Open Help > About", true, [], {}, () => {
+describe("Open Help > About", [], {}, () => {
   test("should see code-server version in about dialog", async ({ codeServerPage }) => {
     // Open using the menu.
     await codeServerPage.navigateMenus(["Help", "About"])