ovf: implement parsing nics

by iterating over the relevant parts and trying to parse out the
'ResourceSubType'. The content of that is not standardized, but I only
ever found examples that are compatible with vmware, meaning it's
either 'e1000', 'e1000e' or 'vmxnet3' (in various capitalizations; thus
the `lc()`)

As a fallback i used e1000, since that is our default too, and should
work for most guest operating systems.

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
Reviewed-by: Fiona Ebner <f.ebner@proxmox.com>

src/PVE/Storage/DirPlugin.pm

@@ -293,7 +293,7 @@ sub get_import_metadata {
 	'create-args' => $res->{qm},
 	'disks' => $disks,
 	warnings => $warnings,
-	net => [],
+	net => $res->{net},
     };
 }