Add ability to use full query to list_calendars

[RogerSelwyn]

In support of this issue - #1168 - this enables full query support on list_calendars. Currently the string of the query is used str(query). I don't know if this will break existing usages, but it seems incorrect to not have full query support.

New code is:

        if query:
            if isinstance(query, str):
                params["$filter"] = query
            else:
                params.update(query.as_params())