Add useParam(event) like useQuery(event)

[mik7up]

To access parameters need to do event.context.params.name.
Why not exists useParam(event)?

[pi0]

useQuery actually parses query from event object but params are already available... But I don't see any reason not to introduce useRouterParams(event) as syntax sugar 👍🏼

[nozomuikuta]

@pi0

This feature looks as easy to implement as #147.
I will submit a PR. 🙋‍♀️