Add netlify redirects support

[Snapstromegon]

This is mainly meant for discussion purposes.

It adds a new middleware netlifyRedirectMiddleware, which uses netlify packages to parse and handle redirects. It's not the best code right now. I'm not really happy with how the onRequestHandler is called internally. It's also missing tests right now.

@zachleat, maybe you can share some first opinions.

fixes #16