Expanding recurring billing events will require a global cursor as opposed to a Registry-scoped cursor, so this CL creates a more generic Cursor type and adds a dual-write for the old RegistryCursor (for both old and new styles) on save. We can then touch any stragglers using the UpdateCursorsCommand and simply drop the old RegistryCursor once all have been migrated.
See [] for migration tracking.
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=121706885
