[Feature]: Update-AzManagementGroupDefault

### Description of the new feature

When you create a new Azure Subscription in Azure AD, by default it will be automatically added under the Root management group. This new subscription will then inherit all the governance conditions, like Azure Policy assignments and Azure role-based access control (RBAC) permissions applied to this management group.

But in many cases, customers require a less or in some cases a more restrictive set of control for their new subscriptions.

Currently we use [REST API](https://docs.microsoft.com/en-us/azure/governance/management-groups/how-to/protect-resource-hierarchy#powershell-sample) to change the default subscription, but we would like to programmatically be able to do this with one single command. Such as Update-AzManagementGroupDefault

[Bicep & ARM](https://docs.microsoft.com/en-us/azure/templates/microsoft.management/managementgroups/settings?tabs=bicep)

### Proposed implementation details (optional)

`Update-AzManagementGroup
-DefaultGroupName
[-DisplayName ]
[-ParentId ]
[-DefaultProfile ]
[-WhatIf]
[-Confirm]
[]`