DEV: use native lazy load on avatars in topic lists and posts (PR #14805)

This PR adds the loading="lazy" attribute to avatars in topic lists and in posts (poster avatar).

Avatars in the topic list are small, so bandwidth is not really the concern. It’s more about prioritizing the requests for the ones that are already in the viewport.

This should be handled by the browser natively. Browser support is currently at 75%.

Safari has this behind a flag. If disabled, it will simply ignore the attribute.

GitHub

CLA assistant check
Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.


Joe seems not to be a GitHub user. You need a GitHub account to be able to sign the CLA. If you have already a GitHub account, please add the email address used for this commit to your account.
You have signed the CLA already but the status is still pending? Let us recheck it.

CLA assistant check
Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.


Joe seems not to be a GitHub user. You need a GitHub account to be able to sign the CLA. If you have already a GitHub account, please add the email address used for this commit to your account.
You have signed the CLA already but the status is still pending? Let us recheck it.