Make split info a status

Is your feature request related to a problem? Please describe.

• https://github.com/nspcc-dev/neofs-api/blob/cf4caf57e98938fddbbee07369ee2999a5dd1ca2/object/service.proto#L303
• https://github.com/nspcc-dev/neofs-api/blob/cf4caf57e98938fddbbee07369ee2999a5dd1ca2/object/service.proto#L479
• https://github.com/nspcc-dev/neofs-api/blob/cf4caf57e98938fddbbee07369ee2999a5dd1ca2/object/service.proto#L678

are response body fields. In general, split info is a particular response payload. However, it is mutex with "normal" data - header and/or payload chunks. This makes it more of a response status

in Go SDK, https://pkg.go.dev/github.com/nspcc-dev/neofs-sdk-go/object#SplitInfoError is an error, and they are also kinda status

Describe the solution you'd like

dedicate new status code for split info. https://github.com/nspcc-dev/neofs-api/blob/cf4caf57e98938fddbbee07369ee2999a5dd1ca2/object/types.proto#L314 itself will be a detail. Deprecate body field. Require servers to respond w/o body depending on the https://github.com/nspcc-dev/neofs-api/blob/cf4caf57e98938fddbbee07369ee2999a5dd1ca2/session/types.proto#L164 field

Describe alternatives you've considered

no more

Additional context

developing new object GET API

Start with the linked object/service.proto response fields and object/types.proto status detail, then inspect session/types.proto for the referenced field. Define the new status-code behavior so split info is carried as a detail, deprecate the response body field, and require the server response behavior described in the issue. Confirm the object GET API declarations consistently reflect this change.