Allow HTML in the link text

I've thought about this a bit and I'm interested in getting this feature added.

However, I don't like the implementation in the patch or the MR. The patch is no good because it's breaking BC. There needs to be a new option added with a default value of false. That's what the MR does, which is good. However, the MR adds an entirely new link_html configuration as well. We can re-use the existing form element for the link text.

So what needs to happen here...

First, I don't like using MRs unless it's a really simple change that won't require any iterating. So let's close the MR and work with patches because that's what I prefer.

Second, we'll need to update existing Kernel tests and add new Kernel tests as well. That's a pain because the Kernel test are clumsy. They are among the first tests I ever wrote and they aren't as clean as they could be.

I just opened a new issue to refactor Kernel tests 📌 Refactor file_download_link Kernel tests Fixed

I'm going to postpone this issue on that one. We can come back to this when that's done and it will be much easier to update and add the required coverage.

Third, we should update the IS to make it clear what the solution is here.

I refactored kernel tests just now so I am un-postponing this one.