Code Quality: Introduced ViewModels for widget controls

[0x5bfa]

Summary

• Added ViewModels for each widget control
• Get rid of possible null dereference warnings
• Follow one class per file rule
• Added Widget prefix to models for widget card items
• Added SideBar prefix to models for sidebar items
• Introduced App.Data.Contracts namespace
• Renamed StatusBarControl to StatusBar
• Improved WidgetsHelper class
• Moved code-behind of HomePage to HomeViewMode
• Renamed IAddressToolbar to IAddressToolbarViewModel
• Renamed ISearchBox to ISearchBoxViewModel

Task Checklist

Steps To Validate Changes

1. Launch the app
2. Go to ...

TODO: Write down

Known Issues

N/A

PR Checklist

• Development: Closes Code Quality: Refactor Widget controls #13210
• Approval: Have discussed with and got approval from the team¹
• Tests: Tested accessibility on the local end
• Deployment: Deployed the app on the local end
• Localization: Modified en-US string resources²
• Co-authors: N/A

Screenshots

UI Improvements:

1. Added no items in container message

Before(Stable)	After(Dev)

2. Adjusted ListViewItem's position

Before(Stable)	After(Dev)

Footnotes

1. If the request hasn't been agreed by the team, this work might be rejected. Make sure that you get approval from the team before opening any PR related the request. ↩

2. If you removed any en-US string resources, make sure that there are no references of those resources. When you add a new en-US string resources, do not make any changes on other languages' resources; Crowdin will do that, instead. ↩

[yaira2]

Can you open a separate PR for the UI changes? This helps the review process and makes it easier to list the improvements in the changelog.