Use Task.Run for async validation methods to improve thread utilization

- Changed from Task.FromResult to Task.Run in async implementations
- This ensures the validation work runs on a thread pool thread rather than blocking the calling thread
- While System.ComponentModel.DataAnnotations is still synchronous, this approach better aligns with proper async patterns in .NET
- Provides better performance characteristics in high-concurrency scenarios (like web applications)
- Maintains exact same functional behavior as before

The underlying validation still uses the synchronous Validator.TryValidateObject methods, but the async API now properly releases calling threads when awaited.

Author: tgharold

src/RecursiveDataAnnotationsValidation/RecursiveDataAnnotationValidator.cs

@@ -53,13 +53,13 @@ public bool TryValidateObjectRecursive(
         /// <param name="validationContext">Validation context.</param>
         /// <param name="validationResults">A collection that will be populated if validation errors occur.</param>
         /// <returns>Returns true if all validation passes.</returns>
-        public Task<bool> TryValidateObjectRecursiveAsync(
+        public async Task<bool> TryValidateObjectRecursiveAsync(
             object obj,
             ValidationContext validationContext,
             List<ValidationResult> validationResults
             )
         {
-            return Task.FromResult(TryValidateObjectRecursive(
+            return await Task.Run(() => TryValidateObjectRecursive(
                 obj,
                 validationResults,
                 validationContext.Items
@@ -71,13 +71,13 @@ List<ValidationResult> validationResults
         /// <param name="validationResults">A collection that will be populated if validation errors occur.</param>
         /// <param name="validationContextItems">Validation context items.</param>
         /// <returns>Returns true if all validation passes.</returns>
-        public Task<bool> TryValidateObjectRecursiveAsync(
+        public async Task<bool> TryValidateObjectRecursiveAsync(
             object obj,
             List<ValidationResult> validationResults,
             IDictionary<object, object> validationContextItems = null
             )
         {
-            return Task.FromResult(TryValidateObjectRecursive(
+            return await Task.Run(() => TryValidateObjectRecursive(
                 obj,
                 validationResults,
                 new HashSet<object>(),