[Refactor] - Update Schemas / Models in Backend

[darmsDD]

Description:

Many schemas don't have a inheritance layer when they should have. For example, User and Entity have a lot of attributes in common, as same as Help, HelpOffer, Campaign.

Acceptance Criteria:

• The new solution has to present, pros and cons in use heritage.
• Update database in production to prevent data loss. Execute a data migration from the old schema to the new ones.

Tasks:

• Search all pros and cons in use heritage with MongoDB.
• Apply changes basing on what were searched
• Migrate data from the old modeling to the new ones.