Describe the bug

My ProjectPeunion solution is crashes, when I'm trying to use NavigationViewItem.Icon property with the CommunityToolkit.WinUI.UI.Controls library. The error is:
Microsoft.UI.Xaml.Markup.XamlParseException: 'XAML parsing failed.'

• Is this bug a regression in the toolkit? If so, what toolkit version did you last see it work:

Steps to Reproduce

• Can this be reproduced in the Sample App? (Either in a sample as-is or with new XAML pasted in the editor.) If so, please provide custom XAML or steps to reproduce. If not, let us know why it can't be reproduced (e.g. more complex setup, environment, dependencies, etc...)

All you need to do:

• Create a new solution with the ProjectReunion version 0.5.5
• nuget: install-package Microsoft.ProjectReunion -Version 0.5.5
• Add NavigationView with one item, that contains the Icon property:

<NavigationView>
   <NavigationView.MenuItems>
      <NavigationViewItem Content="Text" Icon="AddFriend"/>
   </NavigationView.MenuItems>
</NavigationView>

Or clone my sample solution:

• git clone https://github.com/LeftTwixWand/ReunionAppBug.git

Screenshots

Environment

NuGet Package(s): 
 CommunityToolkit.WinUI.UI.Controls Version="7.0.1"
 Microsoft.ProjectReunion Version="0.5.5" 

Windows 10 Build Number:
- [ ] Fall Creators Update (16299)
- [ ] April 2018 Update (17134)
- [ ] October 2018 Update (17763)
- [ ] May 2019 Update (18362)
- [x] May 2020 Update (19041)
- [ ] Insider Build (build number: )

App min and target version:
- [ ] Fall Creators Update (16299)
- [ ] April 2018 Update (17134)
- [ ] October 2018 Update (17763)
- [x] May 2019 Update (18362)
- [ ] May 2020 Update (19041)
- [ ] Insider Build (xxxxx)

Device form factor:
- [x] Desktop
- [ ] Xbox
- [ ] Surface Hub
- [ ] IoT

Visual Studio 
- [ ] 2017 (version: )
- [ ] 2019 (version: ) 
- [x] 2019 Preview (version: 16.10.0 Preview 2.0)