OMode ModelAsString update to make it nullable and rearrangements to avoid breaking change in .Net (#12963)

* Update compute.json

* Update compute.json

* Update compute.json

* Update compute.json

* Update compute.json

trying to arrange for the one ForceDelete breaking change.

* Update compute.json

* Update compute.json

Author: Sandido

specification/compute/resource-manager/Microsoft.Compute/stable/2020-12-01/compute.json

@@ -9110,10 +9110,6 @@
           "type": "boolean",
           "description": "Specifies whether the data disk is in process of detachment from the VirtualMachine/VirtualMachineScaleset"
         },
-        "detachOption": {
-          "$ref": "#/definitions/DetachOption",
-          "description": "Specifies the detach behavior to be used while detaching a disk or which is already in the process of detachment from the virtual machine. Supported values: **ForceDetach**. <br><br> detachOption: **ForceDetach** is applicable only for managed data disks. If a previous detachment attempt of the data disk did not complete due to an unexpected failure from the virtual machine and the disk is still not released then use force-detach as a last resort option to detach the disk forcibly from the VM. All writes might not have been flushed when using this detach behavior. <br><br> This feature is still in preview mode and is not supported for VirtualMachineScaleSet. To force-detach a data disk update toBeDetached to 'true' along with setting detachOption: 'ForceDetach'."
-        },
         "diskIOPSReadWrite": {
           "type": "integer",
           "readOnly": true,
@@ -9125,6 +9121,10 @@
           "readOnly": true,
           "format": "int64",
           "description": "Specifies the bandwidth in MB per second for the managed disk when StorageAccountType is UltraSSD_LRS. Returned only for VirtualMachine ScaleSet VM disks. Can be updated only via updates to the VirtualMachine Scale Set."
+        },
+        "detachOption": {
+          "$ref": "#/definitions/DetachOption",
+          "description": "Specifies the detach behavior to be used while detaching a disk or which is already in the process of detachment from the virtual machine. Supported values: **ForceDetach**. <br><br> detachOption: **ForceDetach** is applicable only for managed data disks. If a previous detachment attempt of the data disk did not complete due to an unexpected failure from the virtual machine and the disk is still not released then use force-detach as a last resort option to detach the disk forcibly from the VM. All writes might not have been flushed when using this detach behavior. <br><br> This feature is still in preview mode and is not supported for VirtualMachineScaleSet. To force-detach a data disk update toBeDetached to 'true' along with setting detachOption: 'ForceDetach'."
         }
       },
       "required": [
@@ -9842,11 +9842,6 @@
           "$ref": "#/definitions/SubResource",
           "description": "Specifies information about the proximity placement group that the virtual machine should be assigned to. <br><br>Minimum api-version: 2018-04-01."
         },
-        "platformFaultDomain": {
-          "type": "integer",
-          "format": "int32",
-          "description": "Specifies the scale set logical fault domain into which the Virtual Machine will be created. By default, the Virtual Machine will by automatically assigned to a fault domain that best maintains balance across available fault domains.<br><li>This is applicable only if the 'virtualMachineScaleSet' property of this Virtual Machine is set.<li>The Virtual Machine Scale Set that is referenced, must have 'platformFaultDomainCount' &gt; 1.<li>This property cannot be updated once the Virtual Machine is created.<li>Fault domain assignment can be viewed in the Virtual Machine Instance View.<br><br>Minimum api‐version: 2020‐12‐01"
-        },
         "priority": {
           "$ref": "#/definitions/priority",
           "description": "Specifies the priority for the virtual machine. <br><br>Minimum api-version: 2019-03-01"
@@ -9889,6 +9884,11 @@
         "extensionsTimeBudget": {
           "type": "string",
           "description": "Specifies the time alloted for all extensions to start. The time duration should be between 15 minutes and 120 minutes (inclusive) and should be specified in ISO 8601 format. The default value is 90 minutes (PT1H30M). <br><br> Minimum api-version: 2020-06-01"
+        },
+        "platformFaultDomain": {
+          "type": "integer",
+          "format": "int32",
+          "description": "Specifies the scale set logical fault domain into which the Virtual Machine will be created. By default, the Virtual Machine will by automatically assigned to a fault domain that best maintains balance across available fault domains.<br><li>This is applicable only if the 'virtualMachineScaleSet' property of this Virtual Machine is set.<li>The Virtual Machine Scale Set that is referenced, must have 'platformFaultDomainCount' &gt; 1.<li>This property cannot be updated once the Virtual Machine is created.<li>Fault domain assignment can be viewed in the Virtual Machine Instance View.<br><br>Minimum api‐version: 2020‐12‐01"
         }
       },
       "description": "Describes the properties of a Virtual Machine."
@@ -10107,7 +10107,7 @@
       ],
       "x-ms-enum": {
         "name": "OrchestrationMode",
-        "modelAsString": false
+        "modelAsString": true
       }
     },
     "ImageOSDisk": {