Provide source for free Store Apps rated "E"

[denelon]

Description of the new feature/enhancement

Support for store Apps based on a manifest was implemented in a previous release. A source needs to be created for these manifests, and it needs to be available to users who have enabled the feature toggle for store Apps.

Proposed technical implementation details (optional)

Build the source package and host it for users who have the feature toggle enabled.

[denelon]

https://github.com/microsoft/winget-cli/releases/tag/v.0.2.2521-preview