Allow extensions to control the redirect policy for the HTTP client (#16162)

This PR extends the extension API with support for controlling the
redirect policy used by the HTTP client.

Release Notes:

- N/A

crates/extension_api/src/extension_api.rs

@@ -21,6 +21,7 @@ pub use wit::{
     },
     zed::extension::http_client::{
         fetch, fetch_stream, HttpMethod, HttpRequest, HttpResponse, HttpResponseStream,
+        RedirectPolicy,
     },
     zed::extension::nodejs::{
         node_binary_path, npm_install_package, npm_package_installed_version,