Make url and http_url work with url.URL.

[bfabio]

Fixes Or Enhances

This makes the url and http_url validations work with url.URL or any newtype that implements the Stringer interface. I'm not familiar with the codebase so it's kind of a PoC PR to see if you think this can be useful.

Make sure that you've checked the boxes below before you submit PR:

• Tests exist or have been written that cover this particular change.

But they don't pass, if this is a feature we want and it's the right approach I can investigate deeper. I suspect the reflection magic isn't working as I expected.

@go-playground/validator-maintainers