CRUD for field of study

[DenisZackharov]

Summary

Same as: ⚠️Parent: #109, with little updates

How it works

Test plan

List of steps to manually test introduced functionality:

1. Login as director with credentials: director@example.com 123456

2. Click to organization name School 13

3. ClickField of studies

4. You can create new field of study, edit and destroy existed

5. Login as teacher with credentials: teacher@example.com 123456

6. Click to organization name School 13

7. Click Field of studies

8. You can see existed field of studies

Checklist:

• [x] I have performed a self-review of my own code
• [x] I have added tests for new functionality
• [ ] My pull request is shorter than 300 lines

Deploy notes

None.