fix(DENG-10047): Add engaged_session flag at the session level to the firefox.com firefox_whatsnew_summary view, & add session filter (#8490)

Author: kwindau

sql/moz-fx-data-shared-prod/firefoxdotcom/firefox_whatsnew_summary/view.sql

@@ -2,10 +2,16 @@ CREATE OR REPLACE VIEW
   `moz-fx-data-shared-prod.firefoxdotcom.firefox_whatsnew_summary`
 AS
 SELECT
+  wns.ga_client_id || "-" || wns.ga_session_id AS visit_identifier,
   wns.*,
-  map.english_text
+  map.english_text,
+  s.engaged_session
 FROM
   `moz-fx-data-shared-prod.firefoxdotcom_derived.firefox_whatsnew_summary_v2` wns
+JOIN
+  `moz-fx-data-shared-prod.firefoxdotcom_derived.ga_sessions_v2` s
+  ON wns.ga_client_id = s.ga_client_id
+  AND wns.ga_session_id = s.ga_session_id
 LEFT JOIN
   (
   --this is an extra safeguard, there should only ever be 1 row per UID & locale
@@ -21,3 +27,5 @@ LEFT JOIN
   ) map
   ON wns.cta_click_uid = map.data_cta_uid
   AND wns.page_location_locale = map.locale
+WHERE
+  REGEXP_CONTAINS(s.ga_client_id || '-' || s.ga_session_id, r"^[0-9]+\.{1}[0-9]+\-{1}[0-9]+$")