Primitives without default parameters in `featuretools.primitives` module break `get_valid_primitives` default code path

A current limitation to `get_valid_primitives` is that it expects every primitive returned by `get_transform_primitives` and `get_aggregation_primitives`. It will try to initialize a primitive without specifying an args, and doesn't handle the case where positional args are required. This adds a requirement that any primitive added to `featuretools.primitives` via the `featuretools_primitives` entry point must have default values set for any init parameters.

It would be good to update `get_valid_primitives` to handle primitives that require positional args, either by excluding them from the default search when it encounters them or to include them anyway in some fashion.