* test: add more unit testing for team member add
* fix(team_endpoints.py): add validation check to prevent same user from being added to team again
prevents duplicates
* fix(team_endpoints.py): raise error if `/team/member_delete` called on member that's not in team
prevent being able to call delete on same member multiple times
* test: update initial tests
* test: fix test
* test: update test to handle no member duplication
