listvms: exclude VMs without datastore_name from manifest.json

On newer ESXI-8x versions, the diskless vCLS machines in an
ESXI-cluster are not stored on a datastore anymore.

Instead, they are placed under `/var/run/crx` on the ESXI-hosts'
filesystem. This can lead to issues with the ESXI-storage not being
activated on the PVE-side [0].

This commit prevents these machines from being included in `manifest.json`.

It also excludes VMs without a datastore string in its configuration.

[0] https://forum.proxmox.com/threads/new-import-wizard-available-for-migrating-vmware-esxi-based-virtual-machines.144023/post-759288

listvms.py

@@ -265,6 +265,20 @@ def main():
     with connect_to_esxi_host(connection_args) as connection:
         data = {}
         for vm in list_vms(connection):
+            # drop vCLS machines
+            vCLS = any(cfg.key == "HDCS.agent"
+                       and cfg.value.lower() == "true"
+                       for cfg in vm.config.extraConfig)
+            if vCLS:
+                continue
+            # drop vms with empty datastore
+            datastore_name, relative_vmx_path = parse_file_path(
+                vm.config.files.vmPathName
+            )
+            if not datastore_name:
+                print(f"Skipping VM (no datastore value): {vm.name}",
+                      file=sys.stderr)
+                continue
             try:
                 fetch_and_update_vm_data(vm, data)
             except Exception as err: