Give every desktop control hover, press and keyboard focus states - #51

The sealed vault's password field showed no change on hover and no
focus ring, and its padding clipped the ring it would have drawn.
Other text fields and dropdowns had no hover either, and the sidebar
rows, secret rows, Seal now, breadcrumbs and links were not Tab stops,
so keyboard focus never reached them.

A new controls module holds one style per kind of control. Text fields
take a Quiet border on hover and the buttons' focus ring. Rows and fill
controls tint on hover and press and draw an inset ring on keyboard
focus. Text links turn Quiet on hover. Switches and checkboxes sit in a
frame that tints on hover and rings when keyboard focus is inside.
Library buttons already had every state and are unchanged. No
transitions were added.