Code Quality: Added Directory.Build.props file

[gumbarros]

Resolved / Related Issues

• [ X] Were these changes approved in an issue or discussion with the project maintainers? In order to prevent extra work, feature requests and changes to the codebase must be approved before the pull request will be reviewed. This prevents extra work for the contributors and maintainers.
  Closes Code Quality: Introduce Directory.build.props for shared properties #14826

Validation
How did you test these changes?

• [X ] Did you build the app and test your changes?

Changes
Added Directory.Build.props file.

Additional comments
Is the constant DISABLE_XAML_GENERATED_MAIN used? I don't added this constant at Directory.build.props and don't know the implications.

[yaira2]

@gumbarros thank you for the contribution, #14826 hasn't been approved yet. For future reference, you can check the status of the issue in the right-hand pane on projects. Alternatively, you can refer to the project board and look for any item with the "Ready to build" status.