Add third party example: Clean Architecture demonstration with Riverpod

[Uuttssaavv]

This Repository demonstrates how to:

• Implement Clean Architecture with Riverpod
• use Riverpod to manage the theme of the application
• Use StateNotifierProvider and Provider to manage the state
• use non-generative method of managing state with Riverpod

[codecov]

Codecov Report

Merging #2750 (f45b829) into master (de164ad) will not change coverage.
The diff coverage is n/a.

Additional details and impacted files

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  Lines        2252     2252           
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  Misses        107      107           

[rrousselGit]

LGTM thanks!