Make ROOT http optional to build without dd_web_display, npdet_info
The version of ROOT in upstream spack does not have http support. This fix builds npdet without dd_web_display, npdet_info when http support is not included in ROOT.
Tested that this indeed doesn't build dd_web_display, npdet_info when ROOT does not have http support. Will check in CI whether it still builds dd_web_display, npdet_info when ROOT does have http support.