editoast: move RollingStockSeparatedImageModel to modelv2

[hamz2a]

closes #6778

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 10 lines in your changes are missing coverage. Please review.

Project coverage is 28.27%. Comparing base (4f7b93f) to head (ddfefc6).
Report is 1 commits behind head on dev.

Files	Patch %	Lines
editoast/src/views/rolling_stocks/mod.rs	0.00%	6 Missing ⚠️
editoast/src/modelsv2/rolling_stock_image.rs	0.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##                dev    #6787   +/-   ##
=========================================
  Coverage     28.27%   28.27%           
  Complexity     2177     2177           
=========================================
  Files          1048     1048           
  Lines        129976   129979    +3     
  Branches       2577     2577           
=========================================
+ Hits          36754    36758    +4     
+ Misses        91733    91732    -1     
  Partials       1489     1489           

Flag	Coverage Δ
core	79.39% <ø> (ø)
editoast	75.89% <0.00%> (+<0.01%)	⬆️
front	8.62% <ø> (ø)
gateway	2.50% <ø> (ø)
railjson_generator	87.26% <ø> (ø)
tests	83.07% <ø> (ø)

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[leovalais]

LGTM, not tested