Decrease the amount of roles and use OpenFGA as backend

[leovalais]

Steps to merge this

• OpenFGA setup
• OpenFGA client add draft OpenFGA client #10504
  • Load models
  • Write tuples
  • Read tuples
• Roles rework

Important

Add the fga binary in editoast's image for both unit tests and easy access to OpenFGA in production.

[codecov-commenter]

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Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.80%. Comparing base (5bd1d85) to head (fd288d3).
Report is 2 commits behind head on dev.

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Additional details and impacted files

@@            Coverage Diff             @@
##              dev   #10503      +/-   ##
==========================================
- Coverage   81.81%   81.80%   -0.01%     
==========================================
  Files        1073     1073              
  Lines      106664   106716      +52     
  Branches      730      730              
==========================================
+ Hits        87267    87300      +33     
- Misses      19358    19377      +19     
  Partials       39       39              

Flag	Coverage Δ
editoast	74.28% <0.00%> (-0.02%)	⬇️
front	89.34% <0.00%> (ø)
gateway	2.18% <0.00%> (ø)
osrdyne	3.28% <0.00%> (ø)
railjson_generator	87.50% <0.00%> (ø)
tests	87.05% <0.00%> (ø)

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