MM-49393 Begin splitting up utils.tsx (#22983)

* Add selectors/urls to Channels

* Create utils/notification_sounds in Channels

* Move Utils.isLinux to UserAgent.isLinux

* Remove Utils.isMac in favour of UserAgent.isMac

* Move cmdOrCtrlPressed and isKeyPressed into new utils/keyboard

* Remove eslint-disable for max-lines in utils.tsx

webapp/channels/src/components/settings_sidebar/settings_sidebar.tsx

@@ -5,7 +5,8 @@ import React, {RefObject} from 'react';
 
 import * as UserAgent from 'utils/user_agent';
 import Constants from 'utils/constants';
-import {a11yFocus, isKeyPressed} from 'utils/utils';
+import {isKeyPressed} from 'utils/keyboard';
+import {a11yFocus} from 'utils/utils';
 
 export type Tab = {
     icon: string;