feat(hogql): cohort filter

[mariusandra]

Problem

One of the things blocking the new event explorer is lack of cohort filters PostHog/meta#81

Changes

Implements cohort filters in a similar way I saw insights and the events table implement cohort filters.

if cohort.is_static:
    sql = "person_id in (SELECT person_id FROM static_cohort_people WHERE cohort_id = {cohort_id})"
else:
    sql = "person_id in (SELECT person_id FROM cohort_people WHERE cohort_id = {cohort_id} GROUP BY person_id, cohort_id, version HAVING sum(sign) > 0)"

Also makes it possible to query from cohort tables

How did you test this code?

Added tests.

[pauldambra]

I can query for cohorts

[pauldambra]

Tangential to this PR but I wonder what stops these definitions and the actual table definitions from diverging other than people being careful

[mariusandra]

People are always careful :).

Good question. Noting really. I added "Lock down" tables for HogQL. Make sure we don't change something users might query on. Expose only what we deem relevant. as a point to the list of all lists.