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

[nodivbyzero]

I've added a few comments suggesting readability improvements.
I recommend keeping the original test functions unchanged and adding new ones for the Stringer type. Also, ensure the GitHub Actions checks pass.

[coveralls]

coverage: 73.663% (-0.01%) from 73.677%
when pulling e7c250a on bfabio:urls
into bc77d03 on go-playground:master.

[bfabio]

I rebased to include #1444 and tweaked it a bit.

@nodivbyzero @go-playground/validator-maintainers