RFC: Fallback placeholder for ImageColumn

[pxlrbt]

Currently ImageColumns height collapses when there is no image set. The default is to take the images size - so that behaviour is expected. But you can also set a size when using ->rounded() or ->size(). This results in rows with different height which looks inconsistent.

I suggest to add an empty div with or without background as a fallback for the cases where the size is defined.

[danharrin]

Wanna do this @pxlrbt ?

[pxlrbt]

Yeah, I just revisited this as well 😅 I'll check whether this is done quickly.

[pxlrbt]

Done!