Move ITrackExtrapolator to a separate dictionary so it can be used in...

Move ITrackExtrapolator to a separate dictionary so it can be used in GaudiPython with DD4hep builds.

Without this fix, loading the ITrackExtrapolator interface in GaudiPython results in the following errors from Cling:

In file included from TrackInterfacesDict dictionary payload:91:
In file included from /home/raaij/stack/Rec/InstallArea/x86_64_v2-centos7-clang12+dd4hep-dbg/include/TrackInterfaces/IMaterialLocator.h:14:
In file included from /home/raaij/stack/Rec/InstallArea/x86_64_v2-centos7-clang12+dd4hep-dbg/include/Event/TrackMaterialIntersection.h:13:
In file included from /home/raaij/stack/LHCb/InstallArea/x86_64_v2-centos7-clang12+dd4hep-dbg/include/DetDesc/ITransportSvc.h:14:
/home/raaij/stack/LHCb/InstallArea/x86_64_v2-centos7-clang12+dd4hep-dbg/include/DetDesc/Material.h:18:7: error: redefinition of 'Intersection' as different kind of symbol
using Intersection  = std::pair<Interval, MaterialPtr>;
      ^
/cvmfs/lhcb.cern.ch/lib/lcg/releases/ROOT/6.26.08-4a0c4/x86_64-centos7-clang12-dbg/include/TGLUtil.h:576:31: note: previous definition is here
std::pair<Bool_t, TGLLine3>   Intersection(const TGLPlane & p1, const TGLPlane & p2);
                              ^

I ran into this while trying to get this script working in DD4hep: https://gitlab.cern.ch/-/snippets/2499