Allow More Permissive Timeout for Pathfinder

[MarkDWilliams]

1. We'll look at the query_graph structure for things that have the structure of a pathfinder query (3 nodes, 2 edges)
2. Add a params or similar JSONField to the Message Model to hold optional parameters
3. Within that params, have "query_type" or something similar and set it to "pathfinder" for queries that match the pattern
4. Look for that query_type the same way we look for agents when doing timeouts currently.