use a separate constructor, fix build

Author: javiercn

src/Components/Components/src/PublicAPI.Unshipped.txt

@@ -1,5 +1,5 @@
 #nullable enable
-Microsoft.AspNetCore.Components.ResourceAsset.ResourceAsset(string! url, System.Collections.Generic.IReadOnlyList<Microsoft.AspNetCore.Components.ResourceAssetProperty!>? properties = null) -> void
+Microsoft.AspNetCore.Components.ResourceAsset.ResourceAsset(string! url) -> void
 Microsoft.AspNetCore.Components.Routing.Router.NotFoundPage.get -> System.Type!
 Microsoft.AspNetCore.Components.Routing.Router.NotFoundPage.set -> void
 Microsoft.AspNetCore.Components.Infrastructure.ComponentsMetricsServiceCollectionExtensions

src/Components/Components/src/ResourceAsset.cs

@@ -12,8 +12,14 @@ namespace Microsoft.AspNetCore.Components;
 /// <param name="url">The URL of the resource.</param>
 /// <param name="properties">The properties associated to this resource.</param>
 [DebuggerDisplay($"{{{nameof(GetDebuggerDisplay)}(),nq}}")]
-public sealed class ResourceAsset(string url, IReadOnlyList<ResourceAssetProperty>? properties = null)
+public sealed class ResourceAsset(string url, IReadOnlyList<ResourceAssetProperty>? properties)
 {
+    /// <summary>
+    /// Initializes a new instance of <see cref="ResourceAsset"/>.
+    /// </summary>
+    /// <param name="url">The URL of the resource.</param>
+    public ResourceAsset(string url) : this(url, null) { }
+
     /// <summary>
     /// Gets the URL that identifies this resource.
     /// </summary>