ipalib: move File command arguments to ipaclient
File arguments are relevant only on the client, on the server they are the
same as Str. Specify the arguments as Str in ipalib.plugins and override
them with File in ipaclient.plugins.
https://fedorahosted.org/freeipa/ticket/4739
Reviewed-By: David Kupka <dkupka@redhat.com>