MySQL query optimization. Added loading component.

components/common/Loading.js

@@ -0,0 +1,13 @@
+import React from 'react';
+import classNames from 'classnames';
+import styles from './Loading.module.css';
+
+export default function Loading({ className }) {
+  return (
+    <div className={classNames(styles.loading, className)}>
+      <div />
+      <div />
+      <div />
+    </div>
+  );
+}