feat: add strict version of uri parsing

[dswij]

This PR adds a strict version of uri parsing to disallow {, } and ".

See hyperium/hyper#3594

[seanmonstar]

I don't think this is a way to go. Part of the point of a specific type is knowing that once parsed, it matches a certain set of characters. Having different constructors could mean two different instances could have separate character sets.

This differs in practice from how HeaderName::from_lowercase(), because all the constructors still force to lowercase, that one constructor just adds an additional validation, instead of coercing to the same character set.