add simple prefix filtering to vmware inventory

Significantly speeds up inventory collection on systems with many
excluded machines.

plugins/inventory/vmware.ini

@@ -23,6 +23,10 @@ guests_only = True
 # caching will be disabled.
 #cache_dir = ~/.cache/ansible
 
+# Specify a prefix filter. Any VMs with names beginning with this string will
+# not be returned.
+# prefix_filter = test_
+
 [auth]
 
 # Specify hostname or IP address of vCenter/ESXi server.  A port may be