chore: more robust membership tests

[Boss-1s]

Solves issue #636

Changes

• Added lists for members and non-members, allowing check for both
• Refactored membership test using any(getattr(...)) and all(getattr(...))

Commented out old test in case, if this passes i'll remove it

Tests

tests/test_memberships.py

[faretek1]

getattr is redundant because the values are guaranteed to be assigned in user.py