Fix the logo in header not being an anchor link.

What does this MR do?

Adds an actual link to the Tanuki in the header instead of a Turbolinks.visit().

Are there points in the code the reviewer needs to double check?

Do we care that this reverts the Safari issue fixed in !2690 (closed)? I feel bad, but it's hacky and there's not a great way to fix it here.

Why was this MR needed?

You couldn't open the home page in a new tab before, it was very annoying.

What are the relevant issue numbers?

Fixes #18604 (closed)

cc: @rspeicher