Convert CommonJS exports to ES6-compatible exports

We use `export default` begrudgingly here. Ideally we'd use just `export`, though this entire SDK expects things to be exported as a default. Instead of breaking everything, we'll sacrifice our export pattern for a smaller diff - a later commit can always do the default export -> regular export conversion.

src/components/views/room_settings/ColorSettings.js

@@ -40,7 +40,7 @@ const ROOM_COLORS = [
 // has a high possibility of being used in the nearish future.
 // Ref: https://github.com/vector-im/riot-web/issues/8421
 
-module.exports = createReactClass({
+export default createReactClass({
     displayName: 'ColorSettings',
 
     propTypes: {

src/components/views/room_settings/UrlPreviewSettings.js

@@ -1,7 +1,8 @@
 /*
 Copyright 2016 OpenMarket Ltd
 Copyright 2017 Travis Ralston
-Copyright 2018-2019 New Vector Ltd
+Copyright 2018, 2019 New Vector 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.
@@ -26,7 +27,7 @@ import dis from "../../../dispatcher";
 import MatrixClientPeg from "../../../MatrixClientPeg";
 
 
-module.exports = createReactClass({
+export default createReactClass({
     displayName: 'UrlPreviewSettings',
 
     propTypes: {