Add geography filter to query endpoint

[Shane98c]

Add support for a geography boolean param to the query endpoint that allows filtering to projects that have boundaries.

need this for both path=projects and path=credits

for example:

 api/query?path=projects%2F&sort=-issued&current_page=1&per_page=100 ... &geography=true

cc @andersy005 @katamartin

frontend pr: carbonplan/offsets-db-web#78