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

Release Notes:

- N/A

crates/gpui/src/app.rs

@@ -1533,4 +1533,8 @@ impl HttpClient for NullHttpClient {
     fn proxy(&self) -> Option<&http_client::Uri> {
         None
     }
+
+    fn type_name(&self) -> &'static str {
+        type_name::<Self>()
+    }
 }