gnoland: RFC private package (non-importable but upgradeable packages)

[moul]

Explore the concept of non-importable but upgradeable packages in Gno, allowing developers to replace a package entirely and discard its previous state.

This upgrade mechanism will not the only one available in the end, but it is easy to implement. We can expect it before the mainnet launch, not after.

Details

• Non-Importable: Mark a package as unimportable by other packages.
• Upgradeable: Allow complete replacement of the package, discarding the previous state.
• Usage Example: Combination of a persistent realm owning the datastore + an upgradeable realm for the logic (controller).
• Special Use Case: Ideal for r/<handle>/home to configure system realms and update Gnoweb. (gnoweb: new u/<handle> page #2189)