UI changes (#6876)

* PLT-7011 - Long channel name truncation

* PLT-7013 - Fixing channel header mobile

* PLT-7012 - Updating quick switch modal on mobile

* PLT-7008 - Channel preferences mobile fix

* PLT-7014 - Increasing tap area for channel desc

webapp/components/navbar.jsx

@@ -698,7 +698,7 @@ export default class Navbar extends React.Component {
                         />
                     </span>
                     <span
-                        className='icon icon__menu'
+                        className='icon icon__menu icon--sidebarHeaderTextColor'
                         dangerouslySetInnerHTML={{__html: menuIcon}}
                         aria-hidden='true'
                     />

webapp/components/quick_switch_modal/quick_switch_modal.jsx

@@ -305,7 +305,7 @@ export default class QuickSwitchModal extends React.PureComponent {
                 <Modal.Header closeButton={true}/>
                 <Modal.Body>
                     {header}
-                    <div className='modal__hint hidden-xs'>
+                    <div className='modal__hint'>
                         {help}
                     </div>
                     <SuggestionBox