Fix T0016 FP: Do not raise inside interface

[pavel-mikula-sonarsource]

This should not raise inside interfaces

public interface ILanguageFacade
{
    IMethodParameterLookup MethodParameterLookup(SyntaxNode invocation, IMethodSymbol methodSymbol); // FP
    IMethodParameterLookup MethodParameterLookup(SyntaxNode invocation, SemanticModel model);   FP
}