Use `ValidationPackageIndex` type from ARCValidationPackages

[kMutagene]

I recently refactored the type modeling in the update script into ARCValidationPackages. once released on nuget, the script should use and serialize those types instead of defining them in the script

[kMutagene]

This turns out to be quite problematic as some dependencies seem to clash. possible solution: isolate Domain types in a separate package to use across the whole ARC ecosystem (maybe even add to the core ARCtrl data model)

[kMutagene]

For reference, different type sources are used:

• ARCValidationPackages types are used in:
  • update-index.fsx script in this repo
  • ARCValidationPackages API (obviously)
• PackageRegistryService types are used in the web API of this repo

obviously, this is a PITA because those need to be kept in sync, and will potentially get worse once a client is generated for the web api.

[kMutagene]

Done, as this repo now publishes the type models as nuget packages