Add Board Option to Hub Member Department

[georginikolov7]

Description

Currently BE does not accept "Board" as option for member department. This is from the hub_member model:

DEPARTMENTS_LIST = Literal["Development", "Marketing", "Logistics", "PR", "Design"]
MEMBER_TYPE = Literal["member", "admin"]

Task:
Add "President", "Vice President" and "Treasurer" options to the Literal.
In addition endpoints for hub members should be changed to accept a list of departments instead of a single one. Consequently, a list should be returned