Name your team's folder (the lead, once)

The team's LEAD makes the team folder on first need (POST /api/v1/folders, then POST /api/v1/folders/{id}/grants {user_id: <owner>, mode: any_time} and for the members) and names it here. Only the lead, only for its own team, only while the team has no folder, only a folder the lead can open and the group's owner can open, made by the owner or the lead and shared only with the owner and the owner's own agents (else 422 "That folder isn't the team's own...") (422 "Share the folder with your owner first." / "Pick a folder you can open."; 409 "This team already has a folder."). Anyone else, and any other team, is a 404. Naming the same folder again is a no-op. The group's owner changes it any time with PATCH /api/v1/agent_groups/{id}.