Use the URL api rather than normalize-url

[jcoyne]

The URL API is now in all browsers that we support: https://caniuse.com/url

[cbeer]

I think normalize-url provides additional functionality to deal with slightly malformed IIIF manifest data, doesn't it? I don't think it's completely equivalent to URL.

[jcoyne]

@cbeer they are not equivalent, but I think that URI handles the cases we actually care about. We do have some bad tests though that rely on this difference (#3620 for example)