Upgrade small_vector from chobo to itlib
The old small_vector.hpp is not c++20 compliant.
Chobolabs repo is archived, and the code is now maintained by iboB old: https://github.com/Chobolabs/chobo-shl new: https://github.com/iboB/itlib/
I've done this for VTK (PR pending), compiles ok, but I haven't checked if these changes compile in the context here.