Remove extra controls directory, add field-control template
Simply base getter/setter, change selectors to use ui property
Add to gallery, add initial SCSS
Break up chart components into separate modules, clean up stats, SCSS

The editable components for FieldDistributionChart
have been moved to a subclass. This class has been
renamed to simply FieldChart
Simplify field-control template, migrate elements to `ui` property
Merge branch 'field-controls' into query-workflow