Get SDK resolver interactivity level from SdkResolverContext (#2390)

* Use reflection via an extension method to get the Interactive property

* Improve readability

src/NuGet.Core/Microsoft.Build.NuGetSdkResolver/ExtensionMethods.cs

@@ -0,0 +1,25 @@
+using System.Reflection;
+using Microsoft.Build.Framework;
+
+namespace Microsoft.Build.NuGetSdkResolver
+{
+    internal static class ExtensionMethods
+    {
+        // In MSBuild 15.9, the SdkResolverContext has an Interactive property.  The value will be gotten through reflection so the MSBuild
+        // references do not need to be updated.
+        private static readonly PropertyInfo SdkResolverContextInteractivePropertyInfo = typeof(SdkResolverContext).GetRuntimeProperty("Interactive");
+
+        /// <summary>
+        /// Determines if the <see cref="SdkResolverContext"/> indicates if there should be no interactivity.
+        /// </summary>
+        /// <param name="context">A <see cref="SdkResolverContext"/> instance.</param>
+        /// <returns><code>true</code> if there should be no interactivity, otherwise <code>false</code>.</returns>
+        public static bool IsNonInteractive(this SdkResolverContext context)
+        {
+            // Determine if SdkResolverContext's Interactive property, defaulting to false
+            var interactive = (bool?) SdkResolverContextInteractivePropertyInfo?.GetValue(context) ?? false;
+
+            return !interactive;
+        }
+    }
+}

src/NuGet.Core/Microsoft.Build.NuGetSdkResolver/NuGetSdkResolver.cs

@@ -128,7 +128,7 @@ public static SdkResult GetSdkResult(SdkReference sdk, object nuGetVersion, SdkR
                     try
                     {
                         var nugetSDKLogger = new NuGetSdkLogger(context.Logger, warnings, errors);
-                        DefaultCredentialServiceUtility.SetupDefaultCredentialService(nugetSDKLogger, nonInteractive: true);
+                        DefaultCredentialServiceUtility.SetupDefaultCredentialService(nugetSDKLogger, nonInteractive: context.IsNonInteractive());
 
                         // Asynchronously run the restore without a commit which find the package on configured feeds, download, and unzip it without generating any other files
                         // This must be run in its own task because legacy project system evaluates projects on the UI thread which can cause RunWithoutCommit() to deadlock