Moonraker route_prefix support

[wilmardo]

As seen in the docs it is possible to configure Moonraker on a subpath:

route_prefix:
#   A prefix prepended to the path for each HTTP endpoint.  For example
#   if the route_prefix is set to moonraker/printer1, then the server info
#   endpoint is available at:
#     http://myprinter.local/moonraker/printer1/server/info
#
#   This is primarily useful for installations that feature multiple instances
#   of Moonraker, as it allows a reverse proxy identify the correct instance based
#   on the path and redirect requests without a rewrite.  Note that frontends must feature
#   support for HTTP endpoints with a route prefix to communicate with Moonraker when
#   this option is set. The default is no route prefix.

https://moonraker.readthedocs.io/en/latest/configuration/

Tested locally with the moonraker.py (also committed the extra arguments I needed to test) see below:

# python ./moonraker.py --host example.com --port 443 --route-prefix moonraker --ssl
moonraker_api.websockets.websocketclient - DEBUG - Websocket changing to state ws_connecting
__main__ - DEBUG - Handling state_changed event to ws_connecting
moonraker_api.websockets.websocketclient - DEBUG - Websocket changing to state ws_connected
__main__ - DEBUG - Handling state_changed event to ws_connected
moonraker_api.websockets.websocketclient - DEBUG - Sending message {"jsonrpc": "2.0", "method": "printer.info", "id": 127157}
moonraker_api.websockets.websocketclient - DEBUG - Received message: WSMessage(type=<WSMsgType.TEXT: 1>, data='{"jsonrpc":"2.0","result":{"state":"shutdown","state_message":"Lost communication with MCU \'mcu\'\\nOnce the underlying issue is corrected, use the\\n\\"FIRMWARE_RESTART\\" command to reset the firmware, reload the\\nconfig, and restart the host software.\\nPrinter is shutdown\\n","hostname":"ender3","klipper_path":"/home/klipper/klipper","python_path":"/home/klipper/klippy-env/bin/python","process_id":65020,"user_id":1000,"group_id":1000,"log_file":"/home/klipper/printer_data/logs/klippy.log","config_file":"/home/klipper/printer_data/config/printer.cfg","software_version":"v0.13.0-375-gba79d72f","cpu_info":"4 core ?"},"id":127157}', extra='')