feat: migrate protocol module to NetworkService (Part 4) (#18084)

* Parse stream protocol handler

* Pipe node stream to mojo

* Merge the parser for headers

* Add ToDict helper to simplify code

* Simplify dispatching logic

* Add an experimental API for returning any type of response

* Fix subscribing event

* URL loaders' lifetime is independent of the factory

* HandleError helper is no longer needed

* Rename "SendResponse" => "StartLoading" to follow naming conventions

* Delete when connection error happens

* Fix cpplint warning

atom/browser/api/atom_api_protocol_ns.cc

@@ -119,6 +119,8 @@ void ProtocolNS::BuildPrototype(v8::Isolate* isolate,
                 &ProtocolNS::RegisterProtocolFor<ProtocolType::kHttp>)
      .SetMethod("registerStreamProtocol",
                 &ProtocolNS::RegisterProtocolFor<ProtocolType::kStream>)
      .SetMethod("registerProtocol",
                 &ProtocolNS::RegisterProtocolFor<ProtocolType::kFree>)
      .SetMethod("unregisterProtocol", &ProtocolNS::UnregisterProtocol)
      .SetMethod("isProtocolRegistered", &ProtocolNS::IsProtocolRegistered)
      .SetMethod("isProtocolHandled", &ProtocolNS::IsProtocolHandled)