Add rel="noopener" for all external links

[XhmikosR]

References

• https://developers.google.com/web/tools/lighthouse/audits/noopener
• https://mathiasbynens.github.io/rel-noopener/
• https://jakearchibald.com/2016/performance-benefits-of-rel-noopener/

There are some links dynamically created in JS; those should have it too.

I have a local branch which takes care of this, but since I'm not familiar with the code base I decided not to submit it. If it'll help, I can make a PR, though.

[brandonkelly]

Craft already sets a referrer policy for all Control Panel pages, so this is not necessary.

cms/src/templates/_layouts/base.html

Line 19 in 2058b4c

<meta name="referrer" content="origin-when-cross-origin">

[XhmikosR]

@brandonkelly: this is not related to the referrer. Please read the links above.

[brandonkelly]

Sorry, misread.

[XhmikosR]

Do you want me to push my current PR? Some changes might not be right, but I can rebase after any feedback.

[brandonkelly]

Sure.

[XhmikosR]

Done in #3202.