BULL-3060: Launchboard BE Teams unit tests
Added unit tests to the teams feature (API and service)
Also includes 2 bug fixes that were discovered by the tests:
- addMember incorrectly sending a Not Found error during a corner case
- toggleMemberIsLeader blocks demotion and promotion of team leaders when there is currently one leader. Changed it so it only rejects the request if the toggle operation is against a current leader, and thus a demotion.
Edited by Douglas Lagemann