Is your feature request related to a problem? Please describe.
Default parameters could not be mutated in the method declaration due to the cause of compile errors. However, since the semantic model was introduced, we could mutate method invocations that make use of default parameters.

Describe the solution you'd like
I'd like to see a mutator that mutates method invocations that use default parameters.

Additional context
An example:

void myMethodWithDefaultParameter(string defaultParam = "Hello Stryker!"){
...
}

When the method is called like this:
myMethodWithDefaultParameter();

I'd expect a mutation like:
myMehodWithDefaultParameter("");