Allowing config flag to turn off javascript controls (#4400)

* Allowing config flag to turn off javascript controls

* lint

* one line, avoiding mutation

* Setting JS fields as readOnly

superset/assets/javascripts/explore/components/ControlHeader.jsx

@@ -14,6 +14,7 @@ const propTypes = {
   onClick: PropTypes.func,
   hovered: PropTypes.bool,
   tooltipOnClick: PropTypes.func,
+  warning: PropTypes.string,
 };
 
 const defaultProps = {
@@ -75,6 +76,19 @@ export default class ControlHeader extends React.Component {
               {this.props.label}
             </span>
             {' '}
+            {(this.props.warning) &&
+              <span>
+                <OverlayTrigger
+                  placement="top"
+                  overlay={
+                    <Tooltip id={'error-tooltip'}>{this.props.warning}</Tooltip>
+                  }
+                >
+                  <i className="fa fa-exclamation-circle text-danger" />
+                </OverlayTrigger>
+                {' '}
+              </span>
+            }
             {(this.props.validationErrors.length > 0) &&
               <span>
                 <OverlayTrigger