Use RuntimeIdentifiers on both heads and libraries, handle pre-net8 identifiers

Author: Arlodotexe

MultiTarget/WinUI.Extra.props

@@ -16,6 +16,10 @@
   <PropertyGroup Condition="'$(IsWinAppSdk)' == 'true'">
     <!-- See https://github.com/microsoft/WindowsAppSDK/issues/3842 -->
     <UseRidGraph>true</UseRidGraph>
+    
+    <RuntimeIdentifiers Condition="$([MSBuild]::GetTargetFrameworkVersion('$(TargetFramework)')) >= 8">win-x86;win-x64;win-arm64</RuntimeIdentifiers> 
+    <RuntimeIdentifiers Condition="8 > $([MSBuild]::GetTargetFrameworkVersion('$(TargetFramework)'))">win10-x86;win10-x64;win10-arm64</RuntimeIdentifiers>
+    <RuntimeIdentifiers>win-x86;win-x64;win-arm64</RuntimeIdentifiers>
   </PropertyGroup>
 
   <PropertyGroup Condition="'$(IsUno)' == 'true'">

ProjectHeads/Head.WinAppSdk.props

@@ -3,7 +3,6 @@
     <OutputType>WinExe</OutputType>
     <TargetFramework>$(WinAppSdkTargetFramework.Split(';')[0])</TargetFramework>
     <Platforms>x86;x64;arm64</Platforms>
-    <RuntimeIdentifiers>win-x86;win-x64;win-arm64</RuntimeIdentifiers>
     <PublishProfile>win-$(Platform).pubxml</PublishProfile>
     <UseWinUI>true</UseWinUI>
     <EnablePreviewMsixTooling>true</EnablePreviewMsixTooling>