An interval_set<DomainT> with std::numeric_limits<DomainT>::max() causes overflows

Consider https://godbolt.org/z/5xKWK9G5o

namespace icl = boost::icl;

```
int main()
{
icl::interval_set i8;
i8.insert(std::numeric_limits::max());
fmt::print("cardinality={}", cardinality(i8));
}
```
this prints `cardinality=18446744073709551361` .
The issue is the cardinality() at concept/interval.hpp which uses `last_next(object)` which overflows to 0, in this case.
With interval_set, things would be worse, since these overflows would be undefined behavior.

I suggest removing the use of `last_next` in any situation where the interval may be the biggest interval in the set.

Reproduce the Godbolt example first, then inspect cardinality() in concept/interval.hpp and its use of last_next(). Done means cardinality() reports the correct value for an interval_set containing max(), without overflow; also check the int case described in the issue.

Written by the indexing model from the issue text.