Resolves an MQTT endpoint to a WebSocket MQTT URL (wss://host/mqtt). Strips any existing protocol or /mqtt path from the input and returns a normalized URL.
Raw MQTT endpoint (e.g. "xxxxx-ats.iot.region.amazonaws.com" or "wss://.../mqtt").
Normalized URL "wss://{host}/mqtt" for use with MQTT over WebSocket.
Error if endpoint is empty.
Resolves an MQTT endpoint to a WebSocket MQTT URL (wss://host/mqtt). Strips any existing protocol or /mqtt path from the input and returns a normalized URL.