Implement downloads page and May 25th timed copy changes (#1653)

* Add initial side nav

* Add Download page as a sub-page under Meth&Data

- udpate S3 file path in .envs
- remove the DownloadPacket component
- move download copy from methodology to download
- modify header to use two types of navs:
--  mobile (with sub-pages) and
-- desktop (without subpages)
- create a SubPageNav component
- add SubPagNav to Meth and Download page
- update snapshots
- add global CSS overide to remove minus sign on mobile nav link accordion as it's permanently open

* Remove the update tag above Public eng button

* Make the 3rd bullet on explore page update on 5/25

* Make the RFI box text change after 5/25/22

* Update site with RFI expired copy, remove Alerts

- add Spanish translations
- update snapshots

* Fix typo on XLS file path

* Refactor HowYouCanHelp to standard form

* Add custom download links with icons

- add new DownloadLink compnent
- add Spanish translations

* Update download file sizes

* Allow meth&data nav link to collapse on mobile

client/src/components/PublicEngageButton/PublicEngageButton.module.scss

@@ -17,6 +17,7 @@
     display: flex;
     flex-direction: column;
     @include u-padding-top(2.5);
+    @include u-margin-top(4);
 
     .link, .link:visited {
         color:white;