[EPIC] detected fields UX tweaks

[Mat Ryer]

Tasks

Beta Give feedback

1. improve empty Detected Fields view #393
   ui +1
   
2. detected fields: remove 'By field' label #398
   ui +1
   
3. If we're hiding detected fields we should tell people why #401
   +0
4. Loading state: When Detected fields is first loading, the page looks broken. We could add a spinner and hide the field bar.

[Joan]

consider skeleton loading for these.
https://www.nngroup.com/articles/skeleton-screens/