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/github.test.ts

@@ -2,7 +2,7 @@ import { test as base } from "@playwright/test"
 import { describe, expect, test } from "./baseFixture"
 
 if (process.env.GITHUB_TOKEN) {
-  describe("GitHub token", true, [], {}, () => {
+  describe("GitHub token", [], {}, () => {
     test("should be logged in to pull requests extension", async ({ codeServerPage }) => {
       await codeServerPage.exec("git init")
       await codeServerPage.exec("git remote add origin https://github.com/coder/code-server")
@@ -16,7 +16,7 @@ if (process.env.GITHUB_TOKEN) {
     })
   })
 
-  describe("No GitHub token", true, [], { GITHUB_TOKEN: "" }, () => {
+  describe("No GitHub token", [], { GITHUB_TOKEN: "" }, () => {
     test("should not be logged in to pull requests extension", async ({ codeServerPage }) => {
       await codeServerPage.exec("git init")
       await codeServerPage.exec("git remote add origin https://github.com/coder/code-server")