Make the renderer automatically add e.g. lazyload to all img tags

[Sebastian-Nielsen]

If it isn't already possible, I would love to see the renderer being capable of automatically adding e.g. lazyload to all img tags.

Perhaps it could be generalized so that the client have the opportunity to specify the attributes to add to a given a tag whenever it is created.

Another use case is to specify you want to add rel="prefetch" to all anchor tags.