Code Cleanup - better handling of external links

[pameyer]

Splitting out from #3337 (comment) :

Short version - it would probably be a good idea to add rel="noopener" to external links, in addition to target="blank".

Another thought that's almost certainly out of scope for this issue, but related to the discussion of consistency with handling external links, would be adding rel="noopener" to external links (recommended by lighthouse for performance / security - https://developers.google.com/web/tools/lighthouse/audits/noopener).

[mheppler]

As @pdurbin noted in his PR comment, we have started to address this issue in adds rel="noopener" attribute to the link formatting in citation.tsv #6249. I will be diligent when reviewing PR that include UI changes which will provide an opportunity to add these rel="noopener" attribures.

I will start a checklist of the places it has been address here, so that if/when this issue gets picked up, we know where this is already done.

• citation.tsv (adds rel="noopener" attribute to the link formatting in citation.tsv #6249)