feat: Allow extra headers to be attached to requests

[zanieb]

Because the target URL for requests made during range reads are constructed from the response URL, they lose credentials attached to the URL. This change allows extra headers to be attached to the requests so users can propagate important headers (such as authorization)

Usage looks roughly like this...

let req = client
    .head(url.clone())
    .build()?

// Copy authorization headers from the HEAD request to subsequent requests
let mut headers = HeaderMap::default();
if let Some(authorization) = req.headers().get("authorization") {
    headers.append("authorization", authorization.clone());
}

let mut reader =
    AsyncHttpRangeReader::from_head_response(client, response, headers)
        .await?;

An alternative option would be to copy authentication from the request URL to the response URL (as in astral-sh/uv#1874 / uv-auth)

Note this is a breaking API change, I don't see an easy way around it e.g. a helper method like with_headers doesn't seem feasible with the way the type is designed.

Needed to resolve astral-sh/uv#1709

[baszalmstra]

This looks good to me, if you can fix CI Id be happy to press the green button.

Thanks!

[baszalmstra]

Nvm CI I have to fix the workflow

[zanieb]

Thanks for the quick merge and release — let me know if you want me to do more i.e. update the tests

(nevermind I see d0530eb now)