SQL Managed Instance Updates

[senavar]

Description

1. When deploying a SQL MI, a subnet must be designated for the instance and a Route Table & NSG must be attached to the subnet. Azure will automatically add routes and rules to the Route Table/NSG. This causes issues when redeploying said Route Table + NSG.
   This is not openly documented and should be noted as part of the module.

2. When trying to enable SQL MI AD Authentication a Service Principal is needed. This Service Principal then needs to be assigned Reader to Azure AD. The creation of the Service Principal is not part of the current module and steps are not documented. Adding the adminstratorObj parameter without doing this results in a failed deployment

3. Module missing things like Zone Redundancy and Backup Storage Redundancy