buildkit WCOW cannot seemingly run `RUN powershell ...`, while vanilla dockerd can about buildkit

[lippertmarkus]

To provide a bit more context:

The following works:

FROM mcr.microsoft.com/windows/servercore:ltsc2022
RUN C:/Windows/System32/WindowsPowerShell/v1.0/powershell.exe write-host Hello

# Outputs: Hello

While this doesn't:

FROM mcr.microsoft.com/windows/servercore:ltsc2022
RUN powershell.exe write-host Hello

# Error: 'powershell.exe' is not recognized as an internal or external command,
# operable program or batch file.

Seems that it doesn't load the PATH correctly. Docker/nerdctl works fine:

nerdctl.exe run --rm -it mcr.microsoft.com/windows/servercore:ltsc2022 powershell hello

# Outputs: hello

Additionally, buildkit seems to persist the PATH issue to the generated image:

# Default servercore
nerdctl run --rm mcr.microsoft.com/windows/servercore:ltsc2022 cmd /c echo %PATH%
# C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Windows\System32\OpenSSH\;C:\Users\ContainerAdministrator\AppData\Local\Microsoft\WindowsApps

# image built with buildkit based on servercore
nerdctl run --rm -it my-buildkit-image:latest cmd /c echo %PATH%
# c:\Windows\System32;c:\Windows

Versions:
containerd v1.7.16
buildkitd v0.13.2

[lippertmarkus]

ref #4895 #3158

[profnandaa]

Sure, we're picking up this discussion from #3158 // For the time-being, a work-around will be adding this at the beginning:

SHELL ["C:\\Windows\\System32\\WindowsPowerShell\\v1.0\\powershell"]

[profnandaa]

/cc. @danielGithinji