Add validation to MG scoped deployment stack New/Set cmdlets. (#25351)

* Add validation to MG scoped deployment stack New/Set cmdlets.

* Update ChangeLog.md

---------

Co-authored-by: NoriZC <[email protected]>

Author: dantedallag

src/Resources/ResourceManager/SdkClient/DeploymentStacksSdkClient.cs

@@ -634,8 +634,7 @@ bool bypassStackOutOfSyncError
                 bypassStackOutOfSyncError
                 );
 
-            // TODO: Enable validation of MG scoped stacks before Create.
-            // ValidateDeploymentStack(deploymentStackModel, deploymentStackName, DeploymentStackScope.ManagementGroup, managementGroupId);
+            ValidateDeploymentStack(deploymentStackModel, deploymentStackName, DeploymentStackScope.ManagementGroup, managementGroupId);
 
             var deploymentStack = DeploymentStacksClient.DeploymentStacks.BeginCreateOrUpdateAtManagementGroup(managementGroupId,
                 deploymentStackName, deploymentStackModel);