All Java createAgreement calls use Participant Groups

### Expected Behaviour
We should be able to send signing steps that contain only a single user as a single member participant, instead of as a participant group with one member.

### Actual Behaviour
When sending a message using the java sdk for an account that does not have access to the Recipient Groups setting "Allow senders to include multiple recipients in a single signing step..", the message will fail, and the api returns: `"code":"BAD_REQUEST","message":"Recipient set is not enabled"`

This seems to be an issue where the ParticipantSetMemberInfo class should be able to set/receive a Name variable.

### Reproduce Scenario (including but not limited to)
#### Steps to Reproduce
Use the Java SDK to send a createAgreement call using single member participant groups to an account with the above setting turned off.

#### Platform and Version
Java SDK v3.0.0

#### Sample Code that illustrates the problem
https://community.adobe.com/t5/acrobat-sign-developer-discussions/individual-recipients-are-always-quot-groups-quot-in-agreements-created-through-api/td-p/14333050

#### Logs taken while reproducing problem

Start with the Java SDK's createAgreement call and the ParticipantSetMemberInfo class, then review the linked reproduction for how single-member participants are represented. Done means a single user is sent as a single member participant without requiring the Recipient Groups setting, and the reported createAgreement scenario succeeds.

Written by the indexing model from the issue text.