applets/notifications: restore padding above the icon, when visible
Reason for the change
We removed row spacing from the base GridLayout, resulting in content on the first row touching the header. This is fine for text which includes internal top padding, but it's not great for the icon which often will not, depending on what exactly the app asks for. Restore the top padding for just the icon.
Test plan
Get a notification from Element, which sends ugly uncropped zero-padded pixmaps as the icon
Screenshots or screen recordings
Now there's equal top and right padding around the icon:
Edited by Nate Graham