Extend `run_as` to allow kwargs

Let's say you have a property type that accepts N positional arguments. A lot of times the module actually takes M inputs (M >= N). The (M - N) arguments not set via positional arguments need to be set in the bound input instance. Most of the time these inputs are parameters (thresholds, max numbers of iterations, etc.) and don't need to be explicitly touched. Nonetheless it would be nice if run_as allowed the user to pass a map of key-values for the non-positional arguments.

It should be noted that the need to change parameters like this is usually a sign of bad property type design, but it's useful for testing purposes.

Locate the implementation and tests for run_as, since no file or test path is named. Review how positional inputs are currently bound, then verify that key-value arguments can set remaining inputs for testing without changing existing positional behavior.