std: add http definitions for Method and Status

[nektro]

starts again the std.http namespace and add definitions for the Method and Status primitives for use in further work and 3rd party libraries

additionally will be used by 910, 2007, 943

[fogti]

switch on Status is currently inconsistent

[daurnimator]

I have a feeling this method could be very misleading (e.g. it might then depend on Vary header)

[fogti]

I think it might make sense to collapse the switch bodies like it's done at other places in the standard library, where all the branches which return true and the branches which return false are grouped; imo this would also make the code more readable, because not as much scrolling is necessary, e.g.

    /// An HTTP method is safe if it doesn't alter the state of the server.
    /// https://developer.mozilla.org/en-US/docs/Glossary/Safe/HTTP
    /// https://datatracker.ietf.org/doc/html/rfc7231#section-4.2.1
    pub fn safe(self: Method) bool {
        return switch (self) {
            .GET, .HEAD, .OPTIONS, .TRACE => true,

            .POST, .PUT, .DELETE, .CONNECT, .PATCH => false,
        };
    }

[daurnimator]

I'm not sure why PUT is in this list?

Infact most PUT responses I've seen have a body on them.

[nektro]

https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods/PUT

[svc-user]

Here's an example of PUT returning a body.

I would still say the stdlib should follow the http standard, but it should not block the ability to get a response body from a PUT request.

[nektro]

it wouldnt stop a client from receiving a PUT body, but it could raise a warning in the server implementation from sending a body

[Inve1951]

Was 499 considered? It's not (yet) standard but commonly used for cancellation. E.g. when the visitor hits ESC in their browser.