Support MakeBitsViewOfInt()

It would be nice if the C++ generated code supported MakeBitsView() types with uint backing storage. We often need to save bitmasks from packet views as integers/enums for passing around in our code. We then need to do bitmasking later without Emboss, which often requires creating new C++ enums. One thing to consider is that we may want the backing storage to have host endianness.

```
uint64_t feature_mask;
auto feature_view = emboss::MakeFeatureView(feature_mask);
bool foo_supported = feature_view.foo_supported().Read();
uint16_t bar = feature_view.bar().Read();
```