Description of the new feature/enhancement

The Microsoft Store requires Microsoft Account (MSA) authentication to acquire previously purchased Apps. The Microsoft Store source is implemented via the REST API.

Running winget install Paint.Net is the canonical example.

Proposed technical implementation details (optional)

The source GET information API should provide the support for MSA authentication to prompt users for an ACK to use MSA authentication for acquiring paid applications. Once this has been accepted by the user, the client should pass an authentication token to the store source on subsequent requests.

microsoft/winget-cli#1339

Note: This may also be a viable authentication mode for other private sources. This is not a duplicate of #37 looking at other authentication mechanisms.