WindowsAppSDKInstaller does not automatically provision the Singleton package

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### Describe the bug

On a fresh virtual machine, if we use the WindowsAppSDKRuntime.exe --quiet (run as SYSTEM account / elevated)

After installing the installer, when we run
Get-AppxPackage -AllUsers | Where-Object Name -like "*WindowsAppRuntime*" | Select Name, Version, SignatureKind, PackageUserInformation

I can see
Name Version
---- -------
Microsoft.WindowsAppRuntime.1.8 8000.770.947.0

for x86 and x64 packages

Windows App Runtime isn’t just one MSIX; it has multiple packages (Framework/Main/Singleton/DDLM)

When installing uses this installer, the Singleton.msix does not actually get provisoned.

"For unpackaged apps, WinAppSDK loads its runtime via framework MSIX packages / dynamic dependencies — those components must exist on the machine. Microsoft explicitly notes that PushNotificationManager depends on an additional Singleton package, and that this affects “self-contained” apps."

Our application is using PushNotificationManager under the Singleton package, and when we use the WindowsAppSDKRuntime.exe --quiet our code returns "Class not found"

When I do a dism.exe /Online /Add-ProvisionedAppxPackage /PackagePath:"...\Microsoft.WindowsAppRuntime.Singleton.1.8.msix" /SkipLicense then restart our software the error goes away.

### Why is this important?

The installer when running WindowsAppSDKRuntime.exe --quiet should install required framework/dlls and should provision all 4 msix packages for ALL users on the machine

### Steps to reproduce the bug

1. Download WindowsAppSDKRuntime.exe
2. Install using WindowsAppSDKRuntime.exe --quiet
3. It doesn't not fully provision all 4 msix packages for all users under the hood

### Actual behavior

_No response_

### Expected behavior

_No response_

### Screenshots

_No response_

### NuGet package version

None

### Windows version

_No response_

### Additional context

_No response_

Start by reproducing the issue on a fresh virtual machine with WindowsAppSDKRuntime.exe --quiet, then use Get-AppxPackage -AllUsers and DISM to compare provisioning of the Framework, Main, Singleton, and DDLM MSIX packages. Done means the installer provisions all four packages for all users and PushNotificationManager no longer returns "Class not found".

Written by the indexing model from the issue text.