Improve Basic/Full icons and rendering

[steersbob]

Widgets generally support a "Basic" view, where only the most important fields are shown, and a "Full" view, where all related configuration is available. This mode-based behavior, and the button that toggles between modes suffers from bad discoverability. Users commonly need to be told that the toggle exists.

The grouping of widget/block fields in the UI is a larger problem that needs significant UX work, but the current toggle is a specific feature that needs improvement.