Implement the TypeSet with the two bitsets (types and exactness) and the related type algebra - union, intersection and complement. 

We should be able to construct TypeSet with BSONType to represent that type and the constructor should take Exactness.

We should be able to construct TypeSet with Value to represent the type of the value (and that is always Exactness::kWidened).

We should be able to construct from MatcherTypeSet too.