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/downloads.test.ts

@@ -3,7 +3,7 @@ import * as path from "path"
 import { clean } from "../utils/helpers"
 import { describe, test, expect } from "./baseFixture"
 
-describe("Downloads (enabled)", true, [], {}, async () => {
+describe("Downloads (enabled)", [], {}, async () => {
   const testName = "downloads-enabled"
   test.beforeAll(async () => {
     await clean(testName)
@@ -25,7 +25,7 @@ describe("Downloads (enabled)", true, [], {}, async () => {
   })
 })
 
-describe("Downloads (disabled)", true, ["--disable-file-downloads"], {}, async () => {
+describe("Downloads (disabled)", ["--disable-file-downloads"], {}, async () => {
   const testName = "downloads-disabled"
   test.beforeAll(async () => {
     await clean(testName)