[Panel] dynamic default query

[mrflix]

How about a query for the default value for for example a page field?

default: pages.filterBy('default', 'true');

My use case: the client creates events on a daily basis. Each event has a location field to select from location pages. They often use the same location, but that default location might change. A possible solution would be to add a default-toggle field to the location blueprint, combined with this query.

[afbora]

Related with https://github.com/getkirby/ideas/issues/434