Refactor HTTP client

[stevenzeck]

Key Change: HTTP Client Refactor

1. Introduced HTTPFetchResponse to clearly separate response metadata (HTTPResponse) from the full response body (Data).
2. Refactored HTTPClient.stream to include an onReceiveResponse async callback, allowing for early interception of headers and potential request cancellation.
3. Improved HTTPResponse with more robust filename extraction from Content-Disposition headers and better support for byte-range requests (added fullContentLength and contentRangeOffset).
4. Updated DefaultHTTPClient with a cleaner implementation using URLSessionDataDelegate.
5. Significant increase in test coverage for the HTTP layer (HTTPClient, HTTPRequest, HTTPResponse, HTTPResource).

Public API Breaking Changes

1. HTTPClient protocol: stream(request:onReceiveResponse:consume:) now requires the onReceiveResponse parameter.
2. HTTPClient extensions: fetch(_:) now returns HTTPResult<HTTPFetchResponse> instead of HTTPResult<HTTPResponse>.
3. HTTPResponse struct: The body: Data? property has been removed. Body data is now accessed via HTTPFetchResponse.body after a fetch call.
4. HTTPStatus struct: The isSuccess property now returns true only for 2xx status codes (200-299). It previously included 3xx codes (200-399).
5. HTTPError enum: The .errorResponse case now takes an HTTPFetchResponse instead of an HTTPResponse.

[stevenzeck]

@mickael-menu any other items you think would be worth addressing here?