Improve images in the chatbar

- Don't show the hide button
- Shrink them to better fit
- Allow a little more maxh height in the chatbar for attachments
- Make sure that the button states work properly when adding and removing images

src/chatbar/RichEditBar.qml

@@ -58,6 +58,7 @@ RowLayout {
     readonly property ChatButtonHelper chatButtonHelper: ChatButtonHelper {
         textItem: root.contentModel.focusedTextItem
         inQuote: root.contentModel.focusType == LibNeoChat.MessageComponentType.Quote
+        hasAttachment: root.contentModel.hasAttachment
     }
 
     signal clicked