Refactor reminder app

[RomanovaPrime]

As a developper I want to have testable and consistent with other examples reminder app.

ACs:

• Refactor the business layer
  • Clear out bloc bodies. Move the logic in state mappers, where possible
  • Add services to extract data manipulations and reduse usage of bloc extensions
  • Add tests for newly created and updated classes
• Refactor the UI layer
  • Replace all possible custom widgets with standart components from widget_toolkit
  • Update golden tests

[nikolay-vasilev-prime]

• Reminder List Scroll View need refactoring, because too many bussines logic is in the UI layer.
• Add Reminder Dialog needs refactoring
• Reminder manage bloc needs refactoring
• Harcoded strings need to be extracted in the l10n
• Dashboard page needs refactoring
• Dashboard bloc can be optimized
• App run configurations are not recognized by Android Studio
• Widget toolkit can be used instead custom views. For example Snackbar can be replaced with bottomsheet dialog.
• Tests will need to be optimized to work with the new improvements.

Estimate: 8-10 days