feat: add locked TTL field to template meta (#8020)

coderd/database/migrations/000128_template_locked_ttl.down.sql

@@ -0,0 +1,3 @@
+BEGIN;
+ALTER TABLE templates DROP COLUMN locked_ttl;
+COMMIT;

coderd/database/migrations/000128_template_locked_ttl.up.sql

@@ -0,0 +1,3 @@
+BEGIN;
+ALTER TABLE templates ADD COLUMN locked_ttl BIGINT NOT NULL DEFAULT 0;
+COMMIT;