Refactor ProgramCodeQuestionController

[isalzh]

Description:

1. Create separate BL service;
2. Implement all required logic for getting/persisting required data from data layer.
3. Move all business-sensitive logic to BL;
4. Create independent data models for particular service;
5. Do not expose any DAL model to Web layer;
6. Cover BL service with unit tests.

Follow "TestCardService" structure as example.

Acceptance Criteria:

ProgramCodeQuestionControllermust not contain any /Data (Repository, ApplicationDbContext, ...) dependency