Figure out mechanism for passing params between WP pages

[patrickmj]

For Chinatown collections, need to build URLs for links to one page to another "static" page that gets the QID from originating URL params and uses it as a param to the shortcode/query to do the SPARQL

See

• https://developer.wordpress.org/reference/functions/get_query_var/

needs

• [ ] template page to hold the query
• [x] reading and passing the GET param to the query in the shortcode
• [x] mechanism to modify the base queries -- basically remake the paramaterized queries from the snowman static site generator