[Core] Missing an API for fixing the aspect ratio of non-image elements

[mikejsavage]

This is pretty minor because like the title suggests you can hack around it with invisible images, but it would be nice to be able to e.g. draw a row (or column) of squares by doing height (or width) 100% + aspect ratio 1 and let clay derive the other dimension.

[nicbarker]

100% agree here, it's been on the list for a while but an aspect ratio box is definitely needed.