Linting XAML using XamlStyler (https://gitter.im/Xavalon/XamlStyler?at=5e558b3d1be0ff01d5ab63b8)

xaml-styler-lint.yaml

# This will allow the job to only execute for Pull Request builds
  condition: eq(variables['Build.Reason'], 'PullRequest')

  steps:
  - task: UseDotNet@2
    displayName: 'Use .Net Core runtime 3.1.x'
    inputs:
      packageType: runtime
      version: 3.1.x

  - powershell: |
     dotnet tool install XamlStyler.Console --tool-path "$(Agent.TempDirectory)"

     &"$(Agent.TempDirectory)\xstyler" -r -d "$(Build.SourcesDirectory)"

     if (git status --porcelain)
     {
         echo "##vso[task.logissue type=error] *** XAML differences were detected. Please ensure to execute XAML Styler on your XAML files ***"
         exit 1
     }
    displayName: 'Execute XAML Styler'

    # You can decide if builds should fail or continue without XAML Styler formatting
    continueOnError: true