Remove various remaining bits of ILAG flows

TypeScript helpfully pointed me towards this dead code, which has been floating
around unused for a while. If we want to bring back ILAG in the future, we can
always revive it from history.

src/stores/SessionStore.js

@@ -1,90 +0,0 @@
-/*
-Copyright 2017 Vector Creations Ltd
-Copyright 2019 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.
-*/
-import dis from '../dispatcher/dispatcher';
-import {Store} from 'flux/utils';
-
-const INITIAL_STATE = {
-    cachedPassword: localStorage.getItem('mx_pass'),
-};
-
-/**
- * A class for storing application state to do with the session. This is a simple flux
- * store that listens for actions and updates its state accordingly, informing any
- * listeners (views) of state changes.
- *
- * Usage:
- *  ```
- *  sessionStore.addListener(() => {
- *   this.setState({ cachedPassword: sessionStore.getCachedPassword() })
- *  })
- *  ```
- */
-class SessionStore extends Store {
-    constructor() {
-        super(dis);
-
-        // Initialise state
-        this._state = INITIAL_STATE;
-    }
-
-    _update() {
-        // Persist state to localStorage
-        if (this._state.cachedPassword) {
-            localStorage.setItem('mx_pass', this._state.cachedPassword);
-        } else {
-            localStorage.removeItem('mx_pass', this._state.cachedPassword);
-        }
-
-        this.__emitChange();
-    }
-
-    _setState(newState) {
-        this._state = Object.assign(this._state, newState);
-        this._update();
-    }
-
-    __onDispatch(payload) {
-        switch (payload.action) {
-            case 'cached_password':
-                this._setState({
-                    cachedPassword: payload.cachedPassword,
-                });
-                break;
-            case 'password_changed':
-                this._setState({
-                    cachedPassword: null,
-                });
-                break;
-            case 'on_client_not_viable':
-            case 'on_logged_out':
-                this._setState({
-                    cachedPassword: null,
-                });
-                break;
-        }
-    }
-
-    getCachedPassword() {
-        return this._state.cachedPassword;
-    }
-}
-
-let singletonSessionStore = null;
-if (!singletonSessionStore) {
-    singletonSessionStore = new SessionStore();
-}
-export default singletonSessionStore;