Update checked headers for new transformers

- If a header was marked as checked before a transformer was added to
  the watcher, mark all headers since the new transformer's starting
  block number as unchecked.

db/migrations/00029_create_checked_logs_table.sql

@@ -0,0 +1,12 @@
+-- +goose Up
+-- SQL in this section is executed when the migration is applied.
+CREATE TABLE public.checked_logs
+(
+    id               SERIAL PRIMARY KEY,
+    contract_address VARCHAR(42),
+    topic_zero       VARCHAR(66)
+);
+
+-- +goose Down
+-- SQL in this section is executed when the migration is rolled back.
+DROP TABLE public.checked_logs;