Windows: ipykernel install prefix not usable for c:\programdata\jupyter

On windows `jupyter --paths` gives

```console
jupyter --paths
config:
C:\tools\miniconda3\envs\pytorch\etc\jupyter
C:\Users\Administrator\.jupyter
C:\Users\Administrator\AppData\Roaming\Python\etc\jupyter
C:\ProgramData\jupyter
data:
C:\tools\miniconda3\envs\pytorch\share\jupyter
C:\Users\Administrator\AppData\Roaming\jupyter
C:\Users\Administrator\AppData\Roaming\Python\share\jupyter
C:\ProgramData\jupyter
runtime:
C:\Users\Administrator\AppData\Roaming\jupyter\runtime
```

And I'd like to use C:\ProgramData\jupyter to store kernelspecs from various different kernels from different envs (using miniconda at the moment)

Trying to do that...

```console
(pytorch) PS C:\Users\Administrator> python -m ipykernel install --name pytorch --prefix=C:\ProgramData\jupyter
0.03s - Debugger warning: It seems that frozen modules are being used, which may
0.00s - make the debugger miss breakpoints. Please pass -Xfrozen_modules=off
0.00s - to python to disable frozen modules.
0.00s - Note: Debugging will proceed. Set PYDEVD_DISABLE_FILE_VALIDATION=1 to disable this validation.
[InstallIPythonKernelSpecApp] WARNING | Installing to C:\ProgramData\jupyter\share\jupyter\kernels, which is not in ['C:\\tools\\miniconda3\\envs\\pytorch\\share\\jupyter\\kernels', 'C:\\Users\\Administrator\\AppData\\Roaming\\jupyter\\kernels', 'C:\\Users\\Administrator\\AppData\\Roaming\\Python\\share\\jupyter\\kernels', 'C:\\ProgramData\\jupyter\\kernels', 'C:\\Users\\Administrator\\.ipython\\kernels']. The kernelspec may not be found.
Installed kernelspec pytorch in C:\ProgramData\jupyter\share\jupyter\kernels\pytorch
```

so somewhere (took a quick look at the code could only find a test that seemed to assume it would) "share" and "jupyter" added into prefix path before "kernels" so this kernel is not found.

moving `C:\ProgramData\jupyter\share\jupyter\kernels\pytorch` to `C:\ProgramData\jupyter\kernels\pytorch` means it gets found

perhaps a --raw-prefix, to which I'd pass C:\ProgramData\jupyter\kernels\ to, that left the prefix as given would solve this?