class concerned :
xAttachedDataManagerAOMDGeneric
xGeneralUnorderedMapDataManager
xUnorderedMapDataManager

- added public type alias :
  using value_type = DATATYPE;
  using key_type = KEYTYPE;
  Rational : usefull for generic programming with datamanagers.

- added member function contains :
bool contains(const KEYTYPE &key) const;
return true if the key is in the datamanager.
rational : when need to know if a key exist in the data manager, calling contains is easier and faster than call getData(key) and check if null.
The name contains is  standard in stl associative container starting at c++20. It complement the old count.

- added member function rangeKey :
xtool::xRange<c_iterKey_t> rangeKey() const;
return the range of key in the container.
rational : avoid calling beginKey() and endKey() in some contexts. Make Datamanagers in sync with other containers of Xfiles.