List shareable people and roles

List the people and roles a share can target, including id, display name, and, for roles, colour and member count. Available to anyone holding a share permission on any content, rather than requiring full user directory access. People are listed only from the caller's own workspace: a franchise child workspace sees its own people, never the parent's or another child workspace's. Email is returned only for people the caller can see with the user view permission; otherwise it is null. A role's member count counts only the listed people.

Notes.

• Besides the screen.view gate, the caller needs at least one share permission somewhere.
• People stop at the child-workspace line: a franchise child workspace sees only its own people, and the parent does not see into a child. email needs user.view reaching that person, else it is null.