[Refactoring]: Refactoring of the class structure of v0.2.0

[alx-net]

In order to make the components of the app less coupled, easier to maintain and add new features, we need to improve the old class structure.

Todos:

• [x] Separate the model, view and controller of the app
• [x] Separate the model, view and controller of the tasks
• [x] Separetely store the content (tasks, descriptions, etc) in a data access service
• [x] Use UI component to line up visual elements within a view consistently