Ensure ExtensionBuilder respects the proxy settings (#14899)

Release Notes:

- N/A

---------

Co-authored-by: Marshall Bowers <elliott.codes@gmail.com>

crates/extension/src/extension_builder.rs

@@ -64,10 +64,10 @@ struct CargoTomlPackage {
 }
 
 impl ExtensionBuilder {
-    pub fn new(cache_dir: PathBuf) -> Self {
+    pub fn new(http_client: Arc<dyn HttpClient>, cache_dir: PathBuf) -> Self {
         Self {
             cache_dir,
-            http: http::client(None),
+            http: http_client,
         }
     }
 

crates/extension/src/extension_store.rs

@@ -243,7 +243,10 @@ impl ExtensionStore {
             extension_index: Default::default(),
             installed_dir,
             index_path,
-            builder: Arc::new(ExtensionBuilder::new(build_dir)),
+            builder: Arc::new(ExtensionBuilder::new(
+                http::client(http_client.proxy().cloned()),
+                build_dir,
+            )),
             outstanding_operations: Default::default(),
             modified_extensions: Default::default(),
             reload_complete_senders: Vec::new(),