fix(mvux): Fix selection not working properly

[dr1rrb]

closes unoplatform/uno#15654

Bugfix

Fix selection not working properly

What is the current behavior?

• ICollectionView.CurrentItem when selecting item right after the currently selected one, causing circular selection
• Invalid coercing of the item index ranges
• Invalid check to determine if an item is currently selected or not

What is the new behavior?

🙃

PR Checklist

• Tested code with current supported SDKs
• Docs have been added/updated which fit documentation template. (for bug fixes / features)
• Unit Tests and/or UI Tests for the changes have been added (for bug fixes / features) (if applicable)
• Wasm UI Tests are not showing unexpected any differences. Validate PR Screenshots Compare Test Run results.
• Contains NO breaking changes
• Updated the Release Notes
• Associated with an issue (GitHub or internal)