Add "spack cd" shell support to cd directly into the staged archive.
Add "spack cd" shell support to cd directly into the staged archive.

mfherbst/spack,iulian787/spack,lgarren/spack,TheTimmy/spack,mfherbst/spack,iulian787/spack,krafczyk/spack,TheTimmy/spack,skosukhin/spack,mfherbst/spack,tmerrick1/spack,EmreAtes/spack,krafczyk/spack,TheTimmy/spack,tmerrick1/spack,EmreAtes/spack,tmerrick1/spack,krafczyk/spack,iulian787/spack,matthiasdiener/spack,krafczyk/spack,lgarren/spack,lgarren/spack,EmreAtes/spack,LLNL/spack,matthiasdiener/spack,LLNL/spack,TheTimmy/spack,tmerrick1/spack,matthiasdiener/spack,skosukhin/spack,skosukhin/spack,tmerrick1/spack,skosukhin/spack,EmreAtes/spack,matthiasdiener/spack,krafczyk/spack,TheTimmy/spack,skosukhin/spack,lgarren/spack,LLNL/spack,mfherbst/spack,EmreAtes/spack,iulian787/spack,lgarren/spack,matthiasdiener/spack,LLNL/spack,mfherbst/spack,LLNL/spack,iulian787/spack