Update UiApplication.cs

[ricaun]

Ignore Application without Library Resources

Pull request type

Please check the type of change your PR introduces:

• [x] Update
• [x] Bugfix
• [x] Feature
• [ ] Code style update (formatting, renaming)
• [ ] Refactoring (no functional changes, no api changes)
• [ ] Build related changes
• [ ] Documentation content changes

What is the current behavior?

If the Application.Current does not contain any Wpf.Ui; resource that application still is used , this PR checks the resources and ignore the Application that does not use Wpf.Ui;.

Issue Number: #1081

What is the new behavior?

By default nothing gonna change: if the MyApp\App.xaml have resources related to the Wpf.Ui library the Application.Current is used like before.

This PR only impact when the library is running outside of the desktop app context.

Other information

[ricaun]

@pomianowski Great 👏🏻 Would be amazing if you release or prerelease in the nuget a new version. 🤗