Force NullabilityInfoContextSupport=true in user projects

To make NRT-based model building work correctly in aggressively
trimmed applications (e.g. MAUI).

Fixes #27474

src/EFCore/EFCore.csproj

@@ -31,6 +31,18 @@ Microsoft.EntityFrameworkCore.DbSet
     <ProjectReference Condition="'$(BuildingByReSharper)' != 'true'" Include="..\EFCore.Analyzers\EFCore.Analyzers.csproj" PrivateAssets="contentfiles;build" />
   </ItemGroup>
 
+  <ItemGroup>
+    <!-- See https://github.com/NuGet/Home/wiki/Allow-package%2D%2Dauthors-to-define-build-assets-transitive-behavior for transitively flowing .props build assets -->
+    <None Include="build\**\*">
+      <Pack>True</Pack>
+      <PackagePath>build</PackagePath>
+    </None>
+    <None Include="build\**\*">
+      <Pack>True</Pack>
+      <PackagePath>buildTransitive</PackagePath>
+    </None>
+  </ItemGroup>
+
   <ItemGroup>
     <None Update="Properties\CoreStrings.Designer.tt">
       <Generator>TextTemplatingFileGenerator</Generator>

src/EFCore/build/net6.0/Microsoft.EntityFrameworkCore.props

@@ -0,0 +1,9 @@
+<Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <PropertyGroup>
+    <!--
+         MAUI (and other size-conscient profiles) trim the nullability attributes, causing the EF Core NRT support to break.
+         This prevents the attributes from being trimmed.
+    -->
+    <NullabilityInfoContextSupport>true</NullabilityInfoContextSupport>
+  </PropertyGroup>
+</Project>