Playwright: Convert sliding-sync test to playwright (#11989)

* Add method to send text message

* Add dockerUrl to HomeServerConfig

* Implement sliding sync proxy

* Convert tests

* Reload page after applying labs feature

* Remove converted files

* Remove timeout

* Remove sliding-sync

* Remove proxy import

* Remove reference to proxy

* wait for load

* Update date

* Convert enableLabsFeature to separate fixture

* Enable feature in fixture

* Skip over config and just write to local-storage

* Rename fixture

* Fix room header test

* Use type inference

* Override config instead of setting localstorage

* Set default language

* Always add labs feature

* Put this one test into a separate describe block

* Move labs lag within describe block

cypress/support/e2e.ts

@@ -38,7 +38,6 @@ import "./iframes";
 import "./timeline";
 import "./network";
 import "./composer";
-import "./proxy";
 import "./axe";
 import "./promise";
 

cypress/support/proxy.ts

@@ -1,58 +0,0 @@
-/*
-Copyright 2022 The Matrix.org Foundation C.I.C.
-
-Licensed under the Apache License, Version 2.0 (the "License");
-you may not use this file except in compliance with the License.
-You may obtain a copy of the License at
-
-    http://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing, software
-distributed under the License is distributed on an "AS IS" BASIS,
-WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-See the License for the specific language governing permissions and
-limitations under the License.
-*/
-
-/// <reference types="cypress" />
-
-import Chainable = Cypress.Chainable;
-import AUTWindow = Cypress.AUTWindow;
-import { ProxyInstance } from "../plugins/sliding-sync";
-import { HomeserverInstance } from "../plugins/utils/homeserver";
-
-declare global {
-    // eslint-disable-next-line @typescript-eslint/no-namespace
-    namespace Cypress {
-        interface Chainable {
-            /**
-             * Start a sliding sync proxy instance.
-             * @param homeserver the homeserver instance returned by startHomeserver
-             */
-            startProxy(homeserver: HomeserverInstance): Chainable<ProxyInstance>;
-
-            /**
-             * Custom command wrapping task:proxyStop whilst preventing uncaught exceptions
-             * for if Docker stopping races with the app's background sync loop.
-             * @param proxy the proxy instance returned by startProxy
-             */
-            stopProxy(proxy: ProxyInstance): Chainable<AUTWindow>;
-        }
-    }
-}
-
-function startProxy(homeserver: HomeserverInstance): Chainable<ProxyInstance> {
-    return cy.task<ProxyInstance>("proxyStart", homeserver);
-}
-
-function stopProxy(proxy?: ProxyInstance): Chainable<AUTWindow> {
-    if (!proxy) return;
-    // Navigate away from app to stop the background network requests which will race with Homeserver shutting down
-    return cy.window({ log: false }).then((win) => {
-        win.location.href = "about:blank";
-        cy.task("proxyStop", proxy);
-    });
-}
-
-Cypress.Commands.add("startProxy", startProxy);
-Cypress.Commands.add("stopProxy", stopProxy);