title: Azure DevOps yaml restore packages to specific directory
body: <p>I have a monorepo with several solutions and trying to configure NuGet yaml to restore to the root directory.
  By defalut <code>task: NuGetCommand@2</code> restores only in the <code>.sln</code> file directory but this will not work for me.</p>
  
  <p>The UI pipelines version has parameter <code>Folder</code> which allows setting a path for packages path. </p>
  
  <p>Is there any parameter for the yaml version?</p>
  
  <p>I tried to set an environment variable - but it's doesn't work.</p>
  
  <p>The yaml code fragment is:</p>
  
  <pre><code>- name: NUGET_PACKAGES
    value: $(build.SourcesDirectory)/
  
  - task: NuGetCommand@2
    displayName: 'Nuget Restore '
    inputs:
      command: 'restore'
      restoreSolution: '**/*.sln'
      feedsToUse: 'select'
      nugetConfigPath: 'packages.config'
      verbosityRestore: 'Normal'
  </code></pre>