(feat): create schema for recording views of feed entities

CREATE TABLE feed_impressions (
  year int,
  month tinyint,
  day tinyint,
  uuid timeuuid,
  entity_urn text,
  position tinyint,
  source text,
  medium text,
  campaign text,
  PRIMARY KEY (year, month, day, uuid, entity_urn)
);
INSERT INTO feed_impressions (year, month, day, uuid, entity_urn, position, source, medium, campaign)
VALUES (2019, 5, 23, NOW(),'urn:activity:123', 3, 'newsfeed/subscriptions', 'organic', 'none')

SELECT * from feed_impressions
  WHERE year=2019
  AND month=5
  AND day=23
  AND uuid>abd576c0-8149-11e9-a21b-6f86601385fd;