Consider supporting other request/response types defined in the function protocol

[daxian-dbw]

FunctionEnvironmentReloadRequest and FunctionEnvironmentReloadResponse were added in the latest protobuf. There are also some other request/response types that we currently don't support. Need to look into what they do and see if we should support them in PS worker.

[joeyaiello]

Just to capture what we discussed, this is really to track usage of all of these request/response types. It's more of an investigation right now than anything.