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/00141_compliance_report_request_mailer_id.sql

@@ -0,0 +1,7 @@
+-- +goose Up
+ALTER TABLE compliance_report_request_mailer
+	ADD COLUMN id SERIAL PRIMARY KEY;
+-- +goose Down
+ALTER TABLE compliance_report_request_mailer
+	DROP COLUMN id;
+