Proxy path fixes (#4548)

* Fix issue where HTTP error status codes are not read.

* Fix issues surrounding sessions when accessed from a proxy.

- Updated vscode args to match latest upstream.
- Fixed issues surrounding trailing slashes affecting base paths.
- Updated cookie names to better match upstream's usage, debuggability.

* Bump vendor.

* Update tests.

* Fix issue where tests lack cookie key.

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

test/utils/globalSetup.ts

@@ -1,4 +1,5 @@
 import { Cookie } from "playwright"
+import { CookieKeys } from "../../src/common/http"
 import { hash } from "../../src/node/util"
 import { PASSWORD, workspaceDir } from "./constants"
 import { clean } from "./helpers"
@@ -27,7 +28,7 @@ export default async function () {
       domain: "localhost",
       expires: -1,
       httpOnly: false,
-      name: "key",
+      name: CookieKeys.Session,
       path: "/",
       sameSite: "Lax",
       secure: false,