Clarify object address field in object context of session token

[alexvanin]

It seems that we currently ignore value of object address in session token (related nspcc-dev/neofs-node#1191).

neofs-api/session/types.proto

Line 44 in f6dad19

neo.fs.v2.refs.Address address = 2 [json_name = "address"];

It is not quite clear what address it should contain in case of DELETE and SEARCH operations. Also is it possible to have wildcard for different addresses? We need more details about that.

[realloc]

We need to clarify the description. When there is no address set, it's interpreted as applicable for all addresses.

Do we need this field to be repeatable?

[alexvanin]

Addition: this field in fact is used by node. By I am not sure it is correct. See useObjectIDFromSession invocation references.

[cthulhu-rider]

We've inspired within nspcc-dev/neofs-node#1420 to make objects in session context repeated. This will allow:

• issue a single session for a group of objects
• gather split-chain within single session

We can either:

1. make existing field repeated: this will allow to issue session for objects from different containers (is this really needed?)
2. deprecate address field, and add refs.ContainerID container_id field and repeated refs.ObjectID id_list
3. intermediate approach with repeated (container_id, repeated object_id) pairs

Thoughts? @alexvanin @realloc