Restore HTTP client transition, but use reqwest everywhere (#19055)

Release Notes:

- N/A

crates/reqwest_client/examples/client.rs

@@ -0,0 +1,41 @@
+use std::time::Instant;
+
+use futures::stream::FuturesUnordered;
+use futures::AsyncReadExt as _;
+use http_client::AsyncBody;
+use http_client::HttpClient;
+use reqwest_client::ReqwestClient;
+use smol::stream::StreamExt;
+
+fn main() {
+    let app = gpui::App::new();
+    app.run(|cx| {
+        cx.spawn(|cx| async move {
+            let client = ReqwestClient::new();
+            let start = Instant::now();
+            let requests = [
+                client.get("https://www.google.com/", AsyncBody::empty(), true),
+                client.get("https://zed.dev/", AsyncBody::empty(), true),
+                client.get("https://docs.rs/", AsyncBody::empty(), true),
+            ];
+            let mut requests = requests.into_iter().collect::<FuturesUnordered<_>>();
+            while let Some(response) = requests.next().await {
+                let mut body = String::new();
+                response
+                    .unwrap()
+                    .into_body()
+                    .read_to_string(&mut body)
+                    .await
+                    .unwrap();
+                println!("{}", &body.len());
+            }
+            println!("{:?}", start.elapsed());
+
+            cx.update(|cx| {
+                cx.quit();
+            })
+            .ok();
+        })
+        .detach();
+    })
+}