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>

package.json

@@ -18,6 +18,7 @@
     "release:github-assets": "./ci/build/release-github-assets.sh",
     "release:prep": "./ci/build/release-prep.sh",
     "test:e2e": "VSCODE_IPC_HOOK_CLI= ./ci/dev/test-e2e.sh",
+    "test:e2e:proxy": "USE_PROXY=1 ./ci/dev/test-e2e.sh",
     "test:unit": "./ci/dev/test-unit.sh --forceExit --detectOpenHandles",
     "test:integration": "./ci/dev/test-integration.sh",
     "test:scripts": "./ci/dev/test-scripts.sh",