Fix SMS app icons and thumbnails

## Summary

Due to the difficult-to-test Qt5 -> Qt6 transition, there were some GUI errors with the SMS app:
- Contact photos were missing
- Attachment previews, if present, were in the place where the contact photo should be

This also takes a shot at fixing the long-standing issue that attachment previews were shown much taller than the row item, drawing over the items above and below. 

## Test Plan

### Before:
As in description, the conversations list items were not correct.

![image](/uploads/f68b662fecd6a4826986ede6e8191470/image.png)

### After:
Contact photos are shown to the left of the text preview, attachment preview, if present, is shown to the far right.

![image](/uploads/95f2b4d6e6ff26371a2f36d97fc3f52b/image.png)

smsapp/conversationlistmodel.cpp

@@ -184,7 +184,7 @@ void ConversationListModel::createRowFromMessage(const ConversationMessage &mess
         const QIcon displayIcon = SmsHelper::getIconForAddresses(rawAddresses);
 
         item->setText(displayNames);
-        item->setData(displayIcon.name(), Qt::DecorationRole);
+        item->setData(displayIcon, Qt::DecorationRole);
         item->setData(message.threadID(), ConversationIdRole);
         item->setData(rawAddresses[0].address(), SenderRole);
     }

smsapp/qml/ConversationList.qml

@@ -191,12 +191,11 @@ Kirigami.ScrollablePage
         delegate: ItemDelegate {
             id: listItem
             text: displayNames
-            icon.name: decoration
             width: view.width
 
             required property string displayNames
             required property string toolTip
-            required property string decoration
+            required property var decoration
             required property var attachmentPreview
             required property int index
             required property var addresses
@@ -223,9 +222,23 @@ Kirigami.ScrollablePage
 
             // Note: Width calcs to account for scrollbar coming and going
             contentItem: RowLayout {
+                id: contentRow
                 spacing: Kirigami.Units.smallSpacing
                 implicitWidth: view.width - Kirigami.Units.largeSpacing
 
+                Kirigami.Icon {
+                    id: contactIcon
+                    source: listItem.decoration
+                }
+
+                // Set width here to force elide and account for scrollbar
+                KirigamiDelegates.TitleSubtitle {
+                    title: listItem.text
+                    subtitle: listItem.toolTip
+                    elide: Text.ElideRight
+                    Layout.fillWidth: true
+                }
+
                 Kirigami.Icon {
                     id: thumbnailItem
                     source: {
@@ -240,21 +253,9 @@ Kirigami.ScrollablePage
                         return listItem.attachmentPreview;
                     }
 
-                    width: Kirigami.Units.iconSizes.small
-                    height: Kirigami.Units.iconSizes.small
-
                     visible: source !== undefined
                 }
-
-                // Set width here to force elide and account for scrollbar
-                KirigamiDelegates.TitleSubtitle {
-                    title: listItem.text
-                    subtitle: listItem.toolTip
-                    elide: Text.ElideRight
-                    implicitWidth: view.width - Kirigami.Units.largeSpacing*2
             }
         }
-
-        }
     }
 }