feat: A nice animation for the onboarding

[g123k]

Hi everyone,

I have tried what we can do with Rive and the gyroscope tonight.
For example, the onboarding, could be way less static than today.

First, the sun is an animation from Rive.
And second, have a look at hills, where they move as I shake my device (thanks to the gyroscope).

Here is a video: https://github.com/openfoodfacts/smooth-app/assets/246838/e3e20b63-9e92-4ca0-bb8b-4e0685cd075d

I don't know if it's worth a merge, but clearly, that is the kind of small thing we can do to make the app more friendly.

[codecov-commenter]

Codecov Report

Merging #4311 (ee7f999) into develop (1cd22a6) will decrease coverage by 0.03%.
The diff coverage is 0.00%.

@@             Coverage Diff             @@
##           develop    #4311      +/-   ##
===========================================
- Coverage    10.80%   10.77%   -0.03%     
===========================================
  Files          287      287              
  Lines        14202    14235      +33     
===========================================
  Hits          1534     1534              
- Misses       12668    12701      +33     

Impacted Files	Coverage Δ
...oth_app/lib/pages/onboarding/reinvention_page.dart	0.00% <0.00%> (ø)

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[teolemon]

The hills, how shall I put it ? 🍑

[g123k]

The hills, how shall I put it ? 🍑

I'm shocked, you have one of those sick minds 🙀