Support new 'requiredProtocolVersion' in DataMessage

* Add new requiredProtocolVersion field to DataMessage

* Message.requiredProtocolVersion, warning if version mot supported

* Update strings; limit width; new left pane preview text

js/modules/signal.js

@@ -65,6 +65,9 @@ const {
 const {
   TypingBubble,
 } = require('../../ts/components/conversation/TypingBubble');
+const {
+  UnsupportedMessage,
+} = require('../../ts/components/conversation/UnsupportedMessage');
 const {
   VerificationNotification,
 } = require('../../ts/components/conversation/VerificationNotification');
@@ -277,6 +280,7 @@ exports.setup = (options = {}) => {
       Message: MediaGalleryMessage,
     },
     TypingBubble,
+    UnsupportedMessage,
     VerificationNotification,
   };