AG-1053 Tidy react examples, make more idiomatic

src-large-data/simpleCellRenderer.jsx

@@ -0,0 +1,16 @@
+import React from 'react';
+import * as PropTypes from 'prop-types';
+
+export default class SimpleCellRenderer extends React.Component {
+    render() {
+        // the class below does nothing, it's just for testing, so we can inspect the dom of
+        // the result and looking for it, to validate that this cellRenderer is actually getting used.
+        return (
+            <span className="simple-cell-renderer">{this.props.value}</span>
+        );
+    }
+}
+
+SimpleCellRenderer.propTypes = {
+    params: PropTypes.object
+};