Arguments could be captured even when signature is unknown

Consider functools.lru_cache; this is a built-in, so signature is not available. However, we still get args and kwargs if we trace the call (as happens often when the decorator is used on a traced class). Currently in the absence of a signature parameters end up being []. I think it's worthwhile to record arguments anyway.

Requires applandinc/appmap#22

For all intents and purposes blocked by #126 -- in CPython native functions are, to my knowledge, the only case where a function signature cannot be obtained. While it might be possible to implement and even test this without that, but it would be pretty useless.

Empieza revisando la ruta de captura de argumentos para las llamadas trazadas que implican functools.lru_cache; después, comprueba la dependencia en applandinc/appmap#22 y el issue bloqueante #126. Se considera terminado cuando args y kwargs se registran incluso cuando no hay una firma de función disponible, en lugar de dejar parameters vacíos.