PHP-1259: MongoDB::listCollections() should support filter option

https://jira.mongodb.org/browse/PHP-1259
I didn't find any evidence of that. We don't allow objects for `$options` arguments, but we do accept arrays and objects anywhere a query document is expected. This is a rare case where we're peeking inside of an options array at a query document, since the "document" would usually be something parsed with zpp directly (typically as "A" or "H").