CommandResult and ValidationResult tweaks (#5772)

* Simplify and align CommandResult and ValidationResult.
  In particular, 1 error per Failure/Invalid.

* Move these files to a common namespace

* Remove unused code

test/Core.Test/AdminConsole/Utilities/Commands/CommandResultTests.cs

@@ -0,0 +1,53 @@
+using Bit.Core.AdminConsole.Utilities.Commands;
+using Bit.Core.AdminConsole.Utilities.Errors;
+using Bit.Test.Common.AutoFixture.Attributes;
+using Xunit;
+
+namespace Bit.Core.Test.AdminConsole.Utilities.Commands;
+
+public class CommandResultTests
+{
+    public class TestItem
+    {
+        public Guid Id { get; set; }
+        public string Value { get; set; }
+    }
+
+    public CommandResult<TestItem> BulkAction(IEnumerable<TestItem> items)
+    {
+        var itemList = items.ToList();
+        var successfulItems = items.Where(x => x.Value == "SuccessfulRequest").ToArray();
+
+        var failedItems = itemList.Except(successfulItems).ToArray();
+
+        var notFound = failedItems.First(x => x.Value == "Failed due to not found");
+        var invalidPermissions = failedItems.First(x => x.Value == "Failed due to invalid permissions");
+
+        var notFoundError = new RecordNotFoundError<TestItem>(notFound);
+        var insufficientPermissionsError = new InsufficientPermissionsError<TestItem>(invalidPermissions);
+
+        return new Partial<TestItem>(successfulItems.ToArray(), [notFoundError, insufficientPermissionsError]);
+    }
+
+    [Theory]
+    [BitAutoData]
+    public void Partial_CommandResult_BulkRequestWithSuccessAndFailures(Guid successId1, Guid failureId1, Guid failureId2)
+    {
+        var listOfRecords = new List<TestItem>
+        {
+            new TestItem() { Id = successId1, Value = "SuccessfulRequest" },
+            new TestItem() { Id = failureId1, Value = "Failed due to not found" },
+            new TestItem() { Id = failureId2, Value = "Failed due to invalid permissions" }
+        };
+
+        var result = BulkAction(listOfRecords);
+
+        Assert.IsType<Partial<TestItem>>(result);
+
+        var failures = (result as Partial<TestItem>).Failures.ToArray();
+        var success = (result as Partial<TestItem>).Successes.First();
+
+        Assert.Equal(listOfRecords.First(), success);
+        Assert.Equal(2, failures.Length);
+    }
+}