Remove unused packages and fix invariant violation on AsyncStore onNotReady (#9404)

* Remove traces of browser-request & mocha

* Remove unused matrix-react-test-utils

* Fix dispatcher invariant violation

* Add null-guard

* Improve types

* Fix null-guard

* Fix issue with authed users going directly to /#/login

test/.eslintrc.js

@@ -1,26 +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.
-*/
-
-module.exports = {
-    env: {
-        mocha: true,
-    },
-
-    // mocha defines a 'this'
-    rules: {
-        "@babel/no-invalid-this": "off",
-    },
-};