Clean up InProcess connector to use same generics as RemoteConnector

[qdot]

With the addition of WASM to the core library, we need an InProcessConnector that can handle message serialization. This is automatically handled in RemoteConnector, but we bypass it in InProcessConnector. It'd be nice if InProcessConnector could just be a ButtplugRemoteConnector with a transport that holds the server, and a passthru serializer for Rust instances (meaning we could swap the serializer to JSON for FFI/WASM cases).