Modernize CaloFuture
- follow changes in match interface -- no need to add std::optional around a type which has a recognizable invalid state
- put tools/algorithms in namespace Calo::Future
- prefer ToolHandles
- remove use of redundant futuredetails::to_string
- prefer free-standing functions over member functions which do not interact with their hosting class
- remove some unused code
- prefer std::is_base_of_v<...> over std::is_base_of<...>::value
- prefer STL algorithms over raw loops
Must be applied in conjunction with LHCb!1990 (merged)