Allow ${WinGetConfigRoot} variable expansion

[msftrubengu]

Allow settings to use the $WinGetConfigRoot variable.

This variable means the directory containing the configuration file and is helpful for units that want reference paths that are relative to the location of the configuration file.

For example, our test resource can use it like this:

properties:
  configurationVersion: 0.2
  resources:
    - resource: xSimpleTestResource/SimpleFileResource
      settings:
        path: '${WinGetConfigRoot}\..\test.txt'
        content: 'Ella baila sola'

To make it PowerShelly, the variable expansion is done ignoring case.

Since this is still in preview, the name of the variable can change when winget configure release.

Microsoft Reviewers: Open in CodeFlow

[JohnMcPMS]

This variable means the current location of the configuration file and is helpful for units that want reference paths that are relative to the location of the configuration file.

I assume you mean "the directory containing the configuration file".