Endpoints to edit staged participant groups

[Whathecode]

The backend now has the notion of "staged" participant groups: sets of participants with assigned master devices before they are deployed. https://github.com/cph-cachet/carp.core-kotlin/issues/255

But, we are still missing endpoints to add/remove/change device assignments in the application service.

[Whathecode]

Once these requests are introduced, RecruitmentService.inviteNewParticipantGroup should be marked as deprecated. The concurrent implementation can lead to errors when the dependent DeploymentService is down. Eventual consistency should be used instead (#295).

[yuanchen233]

I'm not very clear with the plan for staged participation group, it seems to me this notion have 3 purpose:

1. keep track of all deployments of the current study: Recruitmetn.participantGroups
2. manage participant groups before they are invited, and keep data like AssignedParticipantRoles or connectedDevicePreregistrations
3. hold personal information: #479

For (2), those information should be removed after the group is invited, since Deployment is then responsible for role/device assignments. For (3), it sounds redundant with Deployments.ParticipantGroup, since it contains consent and participant data, but we also have issue on #464

Other things to consider:

• combine participant group from study and deployment, and Introduce State Machine like participant group status. right now Deployment.ParticipantGroup in created and invited when Deployment is created through ParticipantGroupService.createAndInviteParticipantGroup. It can go other-way around, we can create participant group, then later on invite it, and create study deployment when the group is invited.
• separate repository/snapshot for staged participant group, otherwise it will result in very frequent update to Recruitment Repository as the number of deployments increase.
• not expose DeploymentServiceRequest.CreateStudyDeployment, study/recruitment can not track deployments created directly through this method. same thing might also applies to Stop.