Resources are serialized as their URN, ID, and package version. Each
Pulumi package is expected to register itself with the SDK. The package
will be invoked to construct appropriate instances of rehydrated
resources. Packages are distinguished by their name and their version.
This is the foundation of cross-process resources.
Related to #2430.
Co-authored-by: Mikhail Shilkov <github@mikhail.io>
Co-authored-by: Luke Hoban <luke@pulumi.com>
Co-authored-by: Levi Blackstone <levi@pulumi.com>
