appearanceTools, and eleven add_theme_support calls

A set of related editor features had eleven separate opt-ins, and appearanceTools turns on the sensible ones together.

{
  "version": 1,
  "settings": {
    "appearanceTools": true
  }
}

// equivalent to enabling: border, colour link, spacing
// padding and blockGap, and typography lineHeight —
// the set grows between versions, which is the point
// and also the risk.

The set is defined by WordPress rather than by the theme, so it grows across versions and a theme using it gets new controls it did not test. That is fine for a theme that intends to follow core and wrong for one with a strict design, which should enumerate the settings it wants. Explicit settings after appearanceTools override it, so the two can be combined — turn the group on and switch off the two that do not fit.