Allow more flexible filtering of behavior sessions

Use cases
- Right now we have hard coded the stage to be either STAGE_FINAL or GRADUATED. But we could want to investigate other stages
- Right now we have hard coded the modality should be `behavior`, but we might want to filter for only sessions with another modality like FIP

The query to docdb already accepts flexible queries and filters, so the only design decision is where to put those filters in the hydra configuration