Guarantee integrity of packages downloaded via a Plugin-Store StoreCode

Guarantee integrity of packages downloaded via a Plugin-Store StoreCode

The package system was unaware of the context of an installation request and permitted the download from unintended package servers.

This can cause the download to be initiated from a different server than the user expected, potentially causing the download of a modified version.

This commit fixes this issue by restricting the package sources to official servers only when the download via the Plugin-Store‘s StoreCode is requested.