The `storage_data_disk` was trying to use vhd_url rather than vhd_uri.
This was causing an error on creating a new data_disk as part of a VM
Also added validation as data_disks can only be 1 - 1023 GB in size
ssh_keys were throwing an error similar to this:
```
* azurerm_virtual_machine.test: [DEBUG] Error setting Virtual Machine
* Storage OS Profile Linux Configuration: &errors.errorString{s:"Invalid
* address to set: []string{\"os_profile_linux_config\", \"0\",
* \"ssh_keys\"}"}
```
This was because of nesting of Set within a Set in the schema. By
changing this to a List within a Set, the schema works as expected. This
means we can now set SSH Keys on VMs. This has been tested using a
remote-exec and a connection block with the ssh key
```
azurerm_virtual_machine.test: Still creating... (2m10s elapsed)
azurerm_virtual_machine.test (remote-exec): Connected!
azurerm_virtual_machine.test (remote-exec): CONNECTED!
```
adminPassword
The Azure API never returns the AdminPAssword (as is correct) from the
Read API call. Therefore on Create, we do not set the AdminPassword of
the vm as part of the state. The Same func is used for Create & Update,
therefore when we changed anything on the VM, we were getting the
following error:
```
statusCode:Conflict
serviceRequestId:f498a6c8-6e7a-420f-9788-400f18078921
statusMessage:{"error":{"code":"PropertyChangeNotAllowed","target":"adminPassword","message":"Changing property 'adminPassword' is not allowed."}}
```
To fix this, we need to excldue the AdminPassword from the Update func
if it is empty
stack72