TS 33.128 CR 0798 - Corrections to User Identifiers Structures

The ASN.1 structures for groups of target identifiers differ resulting in incorrect reporting in some messages. Across the various identifier sets, the ASN.1 structure defines a way to send one or more sequences of identifiers, a single sequence of identifiers or a single identifier. This results in the inability to send multiple identifiers when required. The tables describing the identifier structures also do not match the ASN.1 adding to the potential confusion. This contribution proposes a backwards compatible solution that minimizes the impacts to existing implementations.