WIP: Allow get user info from authority

[xoac]

This PR provides ability to get username and password (userinfo) from Authority.

I proposed 3 ways:

1. two functions username() and password()
2. return new struct UserInfo<'a>
3. return tuple with 2 optional elements username and password.

Personally I would vote for 3 (Of course renamed to user_info).

TODO:

• [ ] Chose method that should be implemented. user_info user_info2 or pair username and password and remove others.
• [ ] Add tests to choose method(s)
• [ ] Add notation to doc about strongly discourage any use with reason that couldn't find in #12

[hronro]

Any update?

[ssrlive]

Please merge this PR. It's useful in many situations.

[xoac]

I proposed 3 different API, if crate maintainers are interested and decide witch one is best I am happy to implement it.

I think @seanmonstar is the main maintainer. If you think this is PR is not useful please close with a reason. Thanks.

[ssrlive]

In order to reduce communication delays, could you please resolve the conflict first? @xoac

[xoac]

I will wait for feedback from maintainers to do any work around this