The Microsoft Store source is added even if the Microsoft Store isn't available.

Brief description of your issue

If you're on a version of Windows that doesn't have the Microsoft Store (LTSC, Server, the weird build Sandbox runs), winget adds the Microsoft Store source even though you can't use it since you can't sign in.

Steps to reproduce

1. Install winget on Windows Sandbox (or real LTSC).
2. Run winget install solitaire.
3. Note that it doesn't work since you aren't signed in.
4. Try to go sign in, and remember that you don't have the Microsoft Store so you can't do that.

Expected behavior

Either the Microsoft Store source won't be added at all so the searches make more sense, or it will do the install without auth (as that's the same behavior that the Microsoft Store app has for free apps).

Actual behavior

Environment

[winget --info]

Windows: Windows.Desktop v10.0.22000.194
Package: Microsoft.DesktopAppInstaller v1.16.12653.0

Any other software?

No source file or test is named. Start by reproducing the issue with winget install solitaire on Windows Sandbox or an affected LTSC system, then trace how the Microsoft Store source is added and how authentication is handled. Done means the source is not offered when the Store is unavailable, or the described unauthenticated free-app install works.