Implement new "read only" room flag

While still maintaining the ability to answer polls and send reactions in channels (when "read only" is false)

src/components/messages/MessageOutgoing.vue

@@ -8,7 +8,7 @@
       <div class="status">{{ event.status }}</div>
     </div>
 
-    <div class="op-button" ref="opbutton" v-if="!event.isRedacted() && !$matrix.currentRoomIsReadOnlyForUser">
+    <div class="op-button" ref="opbutton" v-if="!event.isRedacted() && $matrix.userCanSendMessageInCurrentRoom">
       <v-btn id="btn-show-menu" icon @click.stop="showContextMenu($refs.opbutton)">
         <v-icon>more_vert</v-icon>
       </v-btn>