(Partial) keyword argument forwarding

Split from #1000.

I have a similar use case with Ariadne middleware functions, but with kwargs. In Ariadne, a "resolver" function takes two positional arguments and a varying number of keyword arguments that depend on the API the resolver implements. As the name implies, a middleware function sits between Ariadne and the resolver function and forwards arguments.

Ideally, I would like to type a middleware function as follows:

_P = ParamSpec("_P")
_R = TypeVar("_R")
_T = TypeVar("_T")

def foo_middleware(
    resolver: Callable[Concatenate[_T, GraphQLResolveInfo, _P], _R],
    obj: _T,
    info: GraphQLResolveInfo,
    /,
    **kwargs: _P.kwargs,
) -> _R:
    ...
    return resolver(obj, info, **kwargs)

But currently this isn't possible, because _P.args is "missing".

Comienza leyendo el issue relacionado #1000 y el ejemplo de ParamSpec/Concatenate de este issue. Compara la firma deseada del middleware de Ariadne con el comportamiento actual de reenvío de argumentos con nombre; se considera terminado cuando se admite el reenvío parcial solicitado sin requerir el componente posicional que falta y se ha establecido el comportamiento de tipado correspondiente.