Consider using flags to customize `ArrayOutputMixin`

E.g., imagine that you want to disallow an `ArrayNode` from ever being dynamic. It might be nice to be able to specify that as a template argument to `ArrayOutputMixin`. This would allow is to combine different flags like the one we already added to `ScalarOutputMixin` in https://github.com/dwavesystems/dwave-optimization/pull/271.

Something like
```c++
enum class ArrayMixinFlags {
// default is sometimes dynamic
AlwaysDynamic = 1 << 0,
NeverDynamic = 1 << 1,

// default is not to provide a state implementation
ProvideState = 1 << 2,
};

template
class ArrayOutputMixin : public Base {
template
explicit ArrayOutputMixin(Range&& shape)
: ndim_(shape.size()), shape_(make_shape(std::forward(shape))) {
if constexpr (Flags && ArrayMixinFlags::NeverDynamic) {
// throw an error if dynamic
}
}

...
};

class NeverDynamicNode : public ArrayOutputMixin {
...
};

class NeverDynamicAndDefaultStateNode : public ArrayOutputMixin {
...
};
```