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##### SUMMARY
<!--- Describe the new feature/improvement briefly below -->
vmware_guest_disk should propose `disk_mode` parameter (like vmware_guest module).
The playbook bellow does not raise an error but disk is always added in `persistent` mode, even I set `independent_persistent` for `disk_mode` var.
If it's a bug please could you fix it? If it's not consider it as a feature request :)

##### ISSUE TYPE
- Feature Idea (or maybe a bug)

##### COMPONENT NAME
<!--- Write the short name of the module, plugin, task or feature below, use your best guess if unsure -->
vmware_guest_disk 

##### ADDITIONAL INFORMATION
<!--- Describe how the feature would be used, why it is needed and what it would solve -->

<!--- Paste example playbooks or commands between quotes below -->
```yaml
---
- name: get vm {{ target | upper }} facts
  vmware_guest_facts:
    hostname: "{{ vcenter_hostname }}"
    username: "{{ vcenter_username }}"
    password: "{{ vcenter_password }}"
    datacenter: "{{ datacenter }}"
    validate_certs: no
    name: "{{ target | upper }}"
  register: vm_facts
  delegate_to: localhost

- name: add disk to vm {{ target | upper }}
  vmware_guest_disk:
    hostname: "{{ vcenter_hostname }}"
    username: "{{ vcenter_username }}"
    password: "{{ vcenter_password }}"
    datacenter: "{{ datacenter }}"
    validate_certs: no
    name: "{{ target | upper }}"
    disk:
      - size_gb: "{{ size_gb }}"
        type: "{{ type }}"
        disk_mode: "{{ disk_mode }}"
        scsi_controller: "{{ scsi_controller }}" 
        unit_number: "{{ unit_number }}"
        datastore: "{{ vm_facts.instance.hw_datastores | first }}"
  delegate_to: localhost
```

<!--- HINT: You can also paste gist.github.com links for larger files -->

current_scsi_info = dict()
        results = dict(changed=False, disk_data=None, disk_changes=dict())
        
        for device in vm_obj.config.hardware.device:
            if isinstance(device, tuple(self.scsi_device_type.values())):
                
                if device.busNumber not in current_scsi_info:
                    device_bus_number = 1000 + device.busNumber
                    current_scsi_info[device_bus_number] = dict(disks=dict())
        scsi_changed = False
        for disk in disk_data:
            scsi_controller = disk['scsi_controller'] + 1000
            if scsi_controller not in current_scsi_info and disk['state'] == 'present':
                scsi_ctl = self.create_scsi_controller(disk['scsi_type'], disk['scsi_controller'])
                current_scsi_info[scsi_controller] = dict(disks=dict())
                self.config_spec.deviceChange.append(scsi_ctl)
                scsi_changed = True
        if scsi_changed:
            self.reconfigure_vm(self.config_spec, 'SCSI Controller')
            self.config_spec = vim.vm.ConfigSpec()
            self.config_spec.deviceChange = []
        
        for device in vm_obj.config.hardware.device:
            if isinstance(device, vim.vm.device.VirtualDisk):
                
                if device.controllerKey not in current_scsi_info:
                    current_scsi_info[device.controllerKey] = dict(disks=dict())
                current_scsi_info[device.controllerKey]['disks'][device.unitNumber] = device
        vm_name = self.vm.name
        disk_change_list = []