win32: add fallback to environment vars for system folder

[kasperk81]

Implement fallback to environment variables for system folders in NanoServer, ensuring correct paths when SHGetKnownFolderPath fails.

in base nanoserver image, all values are returning empty

foreach (Environment.SpecialFolder folder in Enum.GetValues(typeof(Environment.SpecialFolder)))
{
    Console.WriteLine($"{folder}: {Environment.GetFolderPath(folder)}")
}

both SHGetFolderPathW and SHGetKnownFolderPath fail with error -2147467259.

environment variables in the base image:
docker run --rm mcr.microsoft.com/windows/nanoserver:ltsc2022 cmd /c "set"

ALLUSERSPROFILE=C:\ProgramData
APPDATA=C:\Users\ContainerUser\AppData\Roaming
CommonProgramFiles=C:\Program Files\Common Files
CommonProgramFiles(x86)=C:\Program Files (x86)\Common Files
CommonProgramW6432=C:\Program Files\Common Files
COMPUTERNAME=594228B8A3DC
ComSpec=C:\Windows\system32\cmd.exe
DriverData=C:\Windows\System32\Drivers\DriverData
LOCALAPPDATA=C:\Users\ContainerUser\AppData\Local
NUMBER_OF_PROCESSORS=4
OS=Windows_NT
Path=C:\Windows\system32;C:\Windows;
PATHEXT=.COM;.EXE;.BAT;.CMD
PROCESSOR_ARCHITECTURE=AMD64
PROCESSOR_IDENTIFIER=AMD64 Family 25 Model 1 Stepping 1, AuthenticAMD
PROCESSOR_LEVEL=25
PROCESSOR_REVISION=0101
ProgramData=C:\ProgramData
ProgramFiles=C:\Program Files
ProgramFiles(x86)=C:\Program Files (x86)
ProgramW6432=C:\Program Files
PROMPT=$P$G
PUBLIC=C:\Users\Public
SystemDrive=C:
SystemRoot=C:\Windows
TEMP=C:\Windows\TEMP
TMP=C:\Windows\TEMP
USERDOMAIN=User Manager
USERNAME=ContainerUser
USERPROFILE=C:\Users\ContainerUser
windir=C:\Windows

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[kasperk81]

@ViktorHofer @akoeplinger I removed this condition, and it's now passing where it was failing before: link to comment. I didn’t update other environment tests since they compare values against win32 SHGetFolderPathW, which returns a general error (-2147467259) on nano server

[kasperk81]

@jkotas analysis shows same error as #108210 but it's not a tracking issue
(this is win32 only change)

[jkotas]

I am leaving it to @dotnet/area-system-runtime owners to do the final signoff and merge.