Add first draft of mailer integration

This adds a bunch of stuff, including setting the organization's Lob
sender address ID, inserting mailer/compliance_report relationships,
adding external id from Lob (or maybe some other provider) and
attempting to load up the pool feature for a site.

db/migrations/00139_organization_lob_address.sql

@@ -0,0 +1,4 @@
+-- +goose Up
+ALTER TABLE organization ADD COLUMN lob_address_id TEXT;
+-- +goose Down
+ALTER TABLE organization DROP COLUMN lob_address_id;