msglist [nfc]: Group message and sender as Column of Rows, not vice versa

Moved widgets around such that the gutters to the
left and right of message contents are ready for
future decorative elements.

Author: sirpengi

lib/widgets/message_list.dart

@@ -899,22 +899,22 @@ class MessageWithPossibleSender extends StatelessWidget {
       onLongPress: () => showMessageActionSheet(context: context, message: message),
       child: Padding(
         padding: const EdgeInsets.symmetric(vertical: 4),
-        child: Row(crossAxisAlignment: CrossAxisAlignment.start, children: [
-          const SizedBox(width: 16),
-          Expanded(
-            child: Column(
-              crossAxisAlignment: CrossAxisAlignment.stretch,
-              children: [
-                if (senderRow != null) ...[
-                  const SizedBox(height: 2),
-                  senderRow,
-                  const SizedBox(height: 4),
-                ],
-                MessageContent(message: message, content: item.content),
-                if ((message.reactions?.total ?? 0) > 0)
-                  ReactionChipsList(messageId: message.id, reactions: message.reactions!)
-              ])),
-          const SizedBox(width: 16),
+        child: Column(children: [
+          if (senderRow != null)
+            Padding(padding: const EdgeInsets.fromLTRB(16, 2, 16, 4),
+              child: senderRow),
+          Row(crossAxisAlignment: CrossAxisAlignment.start, children: [
+            const SizedBox(width: 16),
+            Expanded(
+              child: Column(
+                crossAxisAlignment: CrossAxisAlignment.stretch,
+                children: [
+                  MessageContent(message: message, content: item.content),
+                  if ((message.reactions?.total ?? 0) > 0)
+                    ReactionChipsList(messageId: message.id, reactions: message.reactions!)
+                ])),
+            const SizedBox(width: 16),
+          ]),
         ])));
   }
 }