Instructions on how to manually install WSL without Add-AppPackage

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I am trying to manually install WSL *without* using `Add-AppPackage`. The reason is that service applications (running either as SYSTEM or as a local user, registered under "Services") can not invoke `wsl.exe` because of the sandboxing/permission systems that happens for the `C:\Program Files\WindowsApps` folder / store apps in general. Unfortunately I also need systemd booting capability, so I can not simply using the WSL feature that ships with Windows (it's too old).

To avoid the store app sandboxing, I'm trying to install all the bits of WSL manually with a PowerShell script. Unfortunately I'm stuck on registering COM components - specifically the service server - since store apps have a completely different way of registering their COM components that don't 1:1 align with normal COM registrations. Since there's no source code for WSL, nor debugging symbols on the Microsoft servers, I can't see what interface is missing when I get the following error:

```
Class not registered
Error code: Wsl/0x80040154
```

As far as I can tell, the registrations *look* fine, but since component registration is not documented very well, it's hard to see what I'm missing. I did try installing the WSL feature that ships with Windows, but it apparently doesn't use the same Windows Service/COM architecture that the store version does. This is the script that I've got so far:

(There used to be a PowerShell script here, but I converted it to C#, and it can now be found at: https://src.redpoint.games/redpointgames/rkm/-/blob/wsl-refactor/src/rkm/Components/Windows/WslExtra/WslProvisioningComponent.cs#L156)

Any guidance on what I'm missing here for `wsl.exe` to work would be appreciated.

Start with the C# provisioning code at src/rkm/Components/Windows/WslExtra/WslProvisioningComponent.cs#L156 and the reported Wsl/0x80040154 error. Investigate how the WSL service server COM components are registered for a manual installation rather than through Add-AppPackage. Done means documenting the missing registration steps so wsl.exe works from a service application while retaining systemd support.

Written by the indexing model from the issue text.