disable csv export feature if recaptcha key is not provided

configs/envs/.env.pw

@@ -20,3 +20,4 @@ NEXT_PUBLIC_IS_L2_NETWORK=false
 # api config
 NEXT_PUBLIC_API_HOST=blockscout.com
 NEXT_PUBLIC_STATS_API_HOST=https://stats-test.aws-k8s.blockscout.com
+NEXT_PUBLIC_RE_CAPTCHA_APP_SITE_KEY=xxx

pages/csv-export.tsx

-import type { NextPage } from 'next';
+import type { GetServerSideProps, NextPage } from 'next';
 import Head from 'next/head';
 import React from 'react';
 
+import appConfig from 'configs/app/config';
 import getNetworkTitle from 'lib/networks/getNetworkTitle';
+import type { Props } from 'lib/next/getServerSideProps';
+import { getServerSideProps as getServerSidePropsBase } from 'lib/next/getServerSideProps';
 import CsvExport from 'ui/pages/CsvExport';
 
 const CsvExportPage: NextPage = () => {
@@ -19,4 +22,12 @@ const CsvExportPage: NextPage = () => {
 
 export default CsvExportPage;
 
-export { getServerSideProps } from 'lib/next/getServerSideProps';
+export const getServerSideProps: GetServerSideProps<Props> = async(args) => {
+  if (!appConfig.reCaptcha.siteKey) {
+    return {
+      notFound: true,
+    };
+  }
+
+  return getServerSidePropsBase(args);
+};

ui/address/AddressCsvExportLink.tsx

@@ -4,6 +4,7 @@ import React from 'react';
 
 import type { CsvExportType } from 'types/client/address';
 
+import appConfig from 'configs/app/config';
 import svgFileIcon from 'icons/files/csv.svg';
 import useIsMobile from 'lib/hooks/useIsMobile';
 import LinkInternal from 'ui/shared/LinkInternal';
@@ -17,6 +18,10 @@ interface Props {
 const AddressCsvExportLink = ({ className, address, type }: Props) => {
   const isMobile = useIsMobile();
 
+  if (!appConfig.reCaptcha.siteKey) {
+    return null;
+  }
+
   return (
     <Tooltip isDisabled={ !isMobile } label="Download CSV">
       <LinkInternal