msglist: Add star marker in messages

Author: sirpengi

lib/widgets/message_list.dart

@@ -913,12 +913,21 @@ class MessageWithPossibleSender extends StatelessWidget {
                       if ((message.reactions?.total ?? 0) > 0)
                         ReactionChipsList(messageId: message.id, reactions: message.reactions!)
                     ])),
-                const SizedBox(width: 16),
+                SizedBox(width: 16,
+                  child: message.flags.contains(MessageFlag.starred)
+                    // TODO(#157): fix how star marker aligns with message content
+                    // Design from Figma at:
+                    //   https://www.figma.com/file/1JTNtYo9memgW7vV6d0ygq/Zulip-Mobile?node-id=813%3A28817&mode=dev .
+                    ? Padding(padding: const EdgeInsets.only(top: 4),
+                        child: FittedBox(child: Icon(ZulipIcons.star, color: _kStarColor)))
+                    : null),
               ])),
         ]));
   }
 }
 
+final _kStarColor = const HSLColor.fromAHSL(0.5, 47, 1, 0.41).toColor();
+
 // TODO web seems to ignore locale in formatting time, but we could do better
 final _kMessageTimestampFormat = DateFormat('h:mm aa', 'en_US');