Do not enforce http(s)/ws(s) schema for router url #610

Since Wampy allows passing a custom transport implementation via a WebSocket-like interface, the actual transport is not strictly required to be WebSocket-compatible. In practice, it can be anything — WebSocket, long-polling, or any other protocol, as long as it satisfies the expected interface.

Because of this, enforcing WSS specifically may be too restrictive. We should instead allow passing any valid transport implementation that conforms to the required interface.

In particular, this means we should support custom transports (e.g., a custom WebSocket or non-WebSocket transport) without assuming or enforcing WSS semantics at this level.