Proposal: change ImportBulkRelationships to return a ZedToken #3097

If a user calls WriteSchema and then ImportBulkRelationships and then immediately after CheckPermission with minimize_latency, they will likely get errors of form object definition not found. This is because minimize_latency would have picked a revision that is before the revision at which the schema was written.

The way to work around this is to issue a call with at_least_as_fresh, but ImportBulkRelationshipsResponse doesn't include a zedToken, so one has to include an artifical call (for example: ImportBulk -> ReadSchema(fully_consistent) -> CheckPermission) just to avoid getting an error. This isn't great UX.