feat(smartmigration): add initial smartmigration package with MongoDB and S3 migration runner

ts/types.ts

@@ -0,0 +1,9 @@
+/**
+ * Status of a migration step in a run result.
+ */
+export type TMigrationStatus = 'applied' | 'skipped' | 'failed';
+
+/**
+ * Backend used to persist the migration ledger.
+ */
+export type TLedgerBackend = 'mongo' | 's3';