[projects] Add team member role wrappers

[frankrousseau]

Problem

• Zou supports a role per project on team members ([projects] Allow a different role per project for team members zou#1174) and the client has no wrapper for it

Solution

• add_person_to_team accepts an optional role argument
• New update_team_member_role(project, person, role) wrapper for PUT /data/projects/<project_id>/team/<person_id>; None restores inheritance of the global role