PackageManager: Cache entire SPM workspace state
PackageManager: Cache entire SPM workspace state

This patch fixes a bug that caused SPM to re-fetch all dependencies every
time a script was created or edited (basically any time an Xcode project
had to be re-generated). Running ‘marathon create’ or ‘marathon edit’ is
now a LOT faster.
JohnSundell/Marathon,JohnSundell/Marathon