Update to 26.1 and apply devextreme-examples-template 26.1.3+ changes

Author: AlisherAmonulloev

ASP.NET Core/ASP.NET Core.csproj

@@ -45,7 +45,7 @@
   </Target>
 
   <ItemGroup>
-    <PackageReference Include="DevExtreme.AspNet.Core" Version="25.1.*" />
+    <PackageReference Include="DevExtreme.AspNet.Core" Version="26.1.2-beta" />
   </ItemGroup>
 
 </Project>