Implement API endpoints

[MiKessels]

• [x] https://github.com/KA-Huis/space-management/issues/55
• [ ] https://github.com/KA-Huis/space-management/issues/57
• [ ] https://github.com/KA-Huis/space-management/issues/56
• [ ] https://github.com/KA-Huis/space-management/issues/58

[MiKessels]

I'm following this guide on YouTube for my app. (link contains current progress)