[clarity/consistency] rename /explorev2/ -> /explore/ (#2802)

* rename /explorev2/ -> /explore/

* add redirect for existing explorev2 urls

* fix long line

* remove extra line

* fix missed ref in spec

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

@@ -0,0 +1,47 @@
+import React from 'react';
+import PropTypes from 'prop-types';
+import { Panel } from 'react-bootstrap';
+import InfoTooltipWithTrigger from '../../components/InfoTooltipWithTrigger';
+
+const propTypes = {
+  label: PropTypes.string,
+  description: PropTypes.string,
+  tooltip: PropTypes.string,
+  children: PropTypes.node.isRequired,
+};
+
+const defaultProps = {
+  label: null,
+  description: null,
+  tooltip: null,
+};
+
+export default class ControlPanelSection extends React.Component {
+  renderHeader() {
+    const { label, tooltip } = this.props;
+    let header;
+    if (label) {
+      header = (
+        <div>
+          {label} &nbsp;
+          {tooltip && <InfoTooltipWithTrigger label={label} tooltip={tooltip} />}
+        </div>
+      );
+    }
+    return header;
+  }
+
+  render() {
+    return (
+      <Panel
+        className="control-panel-section"
+        header={this.renderHeader()}
+      >
+        {this.props.children}
+      </Panel>
+    );
+  }
+}
+
+ControlPanelSection.propTypes = propTypes;
+ControlPanelSection.defaultProps = defaultProps;