Cache external addtoany JS library and update the local cache with cron

Patch #11 ✨ Cache external addtoany JS library and update the local cache with cron Needs review worked for me.

Thank you! Committed! 🥃

Thank you for this fix.

Thanks @rockhard76 and @majidali for the patches.

#11 is getting close — great work. It had some issues in dev such as initially missing files so we had to revert, but happy to try another patch rolled for 2.0.x-dev.

Patches welcomed to make this feature robust and release-ready.

I have update the #11 ✨ Cache external addtoany JS library and update the local cache with cron Needs review patch.

1. Added a update hook to download scripts for existing projects using this module.
2. Added install hook to to do the same for new installs.
3. Added schema constraints.
4. Found an issue that Drupal cleanup job deletes everything in public://js directory after 30 days \Drupal\Core\Asset\JsCollectionOptimizer::deleteAll(). Therefore we have to move scripts from public://js/addtoany/menu/ to public://addtoany/menu/

On the patch from #19, I fixed two more issues:
- the library name is addtoany.front (instead of addtoany)
- the path to the static page file was missing a / before the page.js (i.e. addtoany/menu/cached_id/page.js)

I tested this with 1.20 and 2.0 and works well.

One of the servers that I deployed this patch on is using a web proxy to access internet. Drupal is configured properly (ie. http_proxy_config settings), but the patch from #21 failes to retrieve the files because it uses file_get_contents for HTTP requests. in this patch, I replaced file_get_contents with Drupal::httpClient()->get(...)->getBody()->getContents(), which does the same thing, but uses HTTP proxies as configured in Drupal.