LibWeb: Mostly implement ReadableByteStreamController.[[ReleaseSteps]]

Author: https://github.com/mattco98
Commit: bd7809cc18
Pull-request: https://github.com/SerenityOS/serenity/pull/18297
Reviewed-by: https://github.com/linusg

Userland/Libraries/LibWeb/Streams/ReadableByteStreamController.h

@@ -118,6 +118,7 @@ public:
 
     WebIDL::ExceptionOr<JS::GCPtr<WebIDL::Promise>> cancel_steps(JS::Value reason);
     WebIDL::ExceptionOr<void> pull_steps(NonnullRefPtr<ReadRequest>);
+    WebIDL::ExceptionOr<void> release_steps();
 
 private:
     explicit ReadableByteStreamController(JS::Realm&);