Create mocks structure

[BoskiJanusz]

• Modified dependencies.sh to run apt once
• Introduce mock Doctor
• Introduce mock Receptionist
• Introduce factory for Doctor
• Few tests for Doctor
• Few tests for Receptionist

[ziobron]

Thanks @fbtom for Code Review. 🏅 1 XP granted

[ziobron]

Thanks @fbtom for Code Review. 🏅 1 XP granted

[ziobron]

Your PR was merged! 🏅 2 XP granted. Thanks @BoskiJanusz for making course materials better!