[UX] Hide all field labels by default

Describe your issue or idea

I notice that almost every time an image field is added, it's label needs to be hidden. And most of the time, people forget to visit "Manage displays" after adding the field (and maybe that's a cause for another issue).

It seems that we might be able to solve the first part of that problem very easily: can we hide the label for all image fields by default?