fix(rn, polls): Display 'Chat and Polls' as heading when polls enabled

react/features/chat/components/native/Chat.js

         return (
             <JitsiModal
                 headerProps = {{
-                    headerLabelKey: 'chat.title'
+                    headerLabelKey: this.props._isPollsEnabled ? 'chat.titleWithPolls' : 'chat.title'
                 }}
                 modalId = { CHAT_VIEW_MODAL_ID }
                 onClose = { this._onClose }>