Add Response::redirect

[jbr]

The Redirect endpoint is a special case ("always redirect") of the broader need to conditionally redirect based on some logic within a route handler. This PR moves the creation of a temporary redirect into Response and uses that in the Redirect endpoint. Accidentally, this also eliminates a string clone, since set_header only needs a &str.

[prabirshrestha]

Might be better to have redirect_permanent and redirect_temporary to be explicit?

[jbr]

Agreed, and that also seems like a distinction the Redirect endpoint will want to make eventually. I tried to keep the changes small and focused in this PR, but will happily add a second fn. Also considered a second argument with an enum or boolean, but that seems ungainly

[yoshuawuyts]

Could we add an example here?

[yoshuawuyts]

@jbr I like what you're going for with this PR. I think following @prabirshrestha's suggestion to implement both versions might just be easiest; Tide is still in a place where we can issue breaking changes frequently so if we know which API we want, we can implement it.

So my understanding is this would be:

fn redirect_permanent;
fn redirect_temporary;

impl Response {
    fn redirect_permanent;
    fn redirect_temporary;
}

I wonder if it would make sense to shorten the suffix here:

fn redirect_perm;
fn redirect_temp;

impl Response {
    fn redirect_perm;
    fn redirect_temp;
}

[jbr]

Addressed:

• Added redirect_perm
• Renamed redirect to redirect_temp
• Added [hopefully] relatively realistic examples for each

Not [yet] addressed in this PR: Making the same change to the Redirect endpoint / adding a permanent redirect endpoint

[yoshuawuyts]

This is great; thanks heaps!