Use HTTPS and specify Subresource Integrity hash for external assets

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In order to ensure our users are receiving the third-party code we intended, SDG users want thrid-party JS ans CSS assets to use the HTTPS protocol and Subresource Integrity hashes.

In otherwords, update any third part assets from:

<script src="//code.jquery.com/jquery-3.5.1.min.js" crossorigin="anonymous"></script>

to:

<script src="https://code.jquery.com/jquery-3.5.1.min.js" integrity="sha256-9/aliU8dGd2tb6OSsuzixeV4y/faTqgFtohetphbbj0=" crossorigin="anonymous"></script>