[#150] Add sizing token screen in demo app

[ludovic35]

Note: Please transform - [ ] into - (NA) in the description when things are not applicable

Related issues

Description

Motivation & Context

Types of change

• Bug fix (non-breaking which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Refactoring (non-breaking change)
• Breaking change (fix or feature that would change existing functionality)

Previews

Checklist

Contribution

• I have read the contributing guidelines

Accessibility

• My change follows accessibility good practices

Design

• My change respects the design guidelines of Orange Unified Design System

Development

• My change follows the developer guide
• (NA) I have added unit tests to cover my changes (optional)

Documentation

• My change introduces changes to the documentation and/or I have updated the documentation accordingly

Checklist (for Core Team only)

• The evolution have been tested and the project builds for iPhones and iPads
• Code review has been done by reviewers according to CODEOWNERS file
• (NA) Design review has been done
• (NA) Accessibiltiy review has been done
• (NA) Q/A team has tested the evolution
• Documentation has been updated if relevant
• Internal files have been updated if relevant (like CONTRIBUTING, DEVELOP, THIRD_PARTY, CONTRIBUTORS, NOTICE)
• CHANGELOG has been updated respecting keep a changelog rules and reference the issues