refactor: add named parameter support for events, provide websocket

[zehnm]

Provide the websocket handle in events. This allows the integration driver to send request messages to the Remote.
Furthermore, external integration driver can keep track of multiple Remote connections.
Event listeners are wrapped for compatibility: existing event handlers without parameters still work.

BREAKING CHANGE: client event handler using parameters must use the named parameter names.
This mainly affects SUBSCRIBE_ENTITIES and UNSUBSCRIBE_ENTITIES: the parameter must be named entity_ids.

An integration is free to choose which parameters are required. Example:

@api.listens_to(ucapi.Events.SUBSCRIBE_ENTITIES)
async def on_subscribe0() -> None:
    print("SUBSCRIBE_ENTITIES")


@api.listens_to(ucapi.Events.SUBSCRIBE_ENTITIES)
async def on_subscribe1(websocket) -> None:
    print("SUBSCRIBE_ENTITIES with websocket param only", websocket)


@api.listens_to(ucapi.Events.SUBSCRIBE_ENTITIES)
async def on_subscribe2(entity_ids) -> None:
    print("SUBSCRIBE_ENTITIES with entity_ids param only:", entity_ids)


@api.listens_to(ucapi.Events.SUBSCRIBE_ENTITIES)
async def on_subscribe(websocket, entity_ids) -> None:
    print("SUBSCRIBE_ENTITIES", entity_ids, websocket)

This change is required for PR #47