Fix support for AnythingOfTypeArgument.

The expected and actual values in Diff are in opposite order.

We need to compare the the type of the expected with AnythingOfTypeArgument, and then the type of the actual with the type set in the AnythingOfTypeArgument.
m.On("MyFunction", mock.AnythingOfType("*MyType"), 123).Return(true, nil)

When pointers to structs are used, reflect.TypeOf(actual).Name() is used, it returns an empty string, but String() returns the right value.