UWP app does not work with Windows Application Packaging Project
## 🐛 Bug Report

I have a problem with Windows Application Packaging Project which has UWP app with MvvmCross set as entry point. 

### Expected behavior

Deploying Windows Application Packaging launches UWP app. 

### Reproduction steps

I described my problem at stackoverflow before I found out the problem is probably in MvvmCross package: https://stackoverflow.com/questions/69476713/windows-10-uwp-app-crash-at-start-faulting-module-name-windows-ui-xaml-dll.

In a nutshell I using UWP app which using MvvmCros and it is scaffolded with MvxScaffolding but for some reason I need Application Packaging Project which has UWP app set as entry poit and FullTrust app which UWP app calling in backgroud.

I have sample project for reproduce this problem [HERE](https://github.com/pinkysek/SampleApp). When you set SampleApp.Package as start up project and run it crash but if I change in SamleApp.Package as entry point app SampleApp.UWP.Blank project which does not usin MvvmCrosss it works.

### Configuration

**Version:** 8.x (but it was same with 6x but I updated version).

**Platform:** 
- [ ] :iphone: iOS
- [ ] :robot: Android
- [ ] :checkered_flag: WPF
- [x] :earth_americas: UWP
- [ ] :apple: MacOS
- [ ] :tv: tvOS
- [ ] :monkey: Xamarin.Forms
