Make images in content default to their intrinsic size (rather than 100% of the container) if they are not resized

[sync-by-unito]

Currently the behaviour is:

• If you resize an image before submitting, it will use a width that is a fixed % (<100%) of the parent container
• If you don't resize it, it will use a width of 100% of the parent

The behaviour should be something like:

• If you don't resize it, it uses it's natural resolution (up to 100% of parent width)
• If you do resize it, it still uses a fixed % of the parent container

It's possible the behaviour on resize will seem odd once the un-resized behaviour is fixed (e.g. if you use a really small image and don't resize it, then it will be small when published, but if you resize it a bit it will be almost 100% of the parent). So maybe it's worth changing that at the same time

┆Issue is synchronized with this Asana task by Unito