Add property group to suppress IL2026 warnings for Uno behaviors

Author: Arlodotexe

ProjectHeads/App.Head.Uno.props

@@ -6,6 +6,11 @@
   <Import Project="$(MSBuildThisFileDirectory)\App.Head.props" />
   <Import Project="$(MSBuildThisFileDirectory)\..\MultiTarget\PackageReferences\Uno.props" />
   <Import Project="$(MSBuildThisFileDirectory)\..\MultiTarget\WinUI.Extra.props" />
+
+  <PropertyGroup Condition="'$(IsUno)' == 'true'">
+    <!-- Code generated by Uno.UI.SourceGenerators creates AoT-unsafe code when Behaviors are used.  -->
+    <WarningsNotAsErrors>$(NoWarn);IL2026</WarningsNotAsErrors>
+  </PropertyGroup>
 
   <!--
       Import Uno dependencies for all deployable Uno-based Labs project heads.