front: convert base64 encoded map image to jpeg

[Akctarus]

closes #8978

The map image was just base64 encoded, now we convert it to jpeg and reduce its quality a little, saving up to 500KB

[codecov-commenter]

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Codecov Report

Attention: Patch coverage is 12.50000% with 56 lines in your changes missing coverage. Please review.

Project coverage is 37.51%. Comparing base (5a6ae29) to head (1fe68d2).
Report is 8 commits behind head on dev.

Files with missing lines	Patch %	Lines
...cations/stdcm/utils/formatSimulationReportSheet.ts	21.05%	30 Missing ⚠️
...cations/stdcm/components/SimulationReportSheet.tsx	0.00%	25 Missing and 1 partial ⚠️

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Additional details and impacted files

@@             Coverage Diff              @@
##                dev    #9029      +/-   ##
============================================
- Coverage     37.53%   37.51%   -0.02%     
  Complexity     2242     2242              
============================================
  Files          1256     1256              
  Lines        114937   114999      +62     
  Branches       3271     3271              
============================================
+ Hits          43143    43147       +4     
- Misses        69848    69906      +58     
  Partials       1946     1946              

Flag	Coverage Δ
core	74.78% <ø> (ø)
editoast	72.04% <ø> (-0.02%)	⬇️
front	15.57% <12.50%> (-0.01%)	⬇️
gateway	2.22% <ø> (ø)
osrdyne	2.56% <ø> (ø)
railjson_generator	87.49% <ø> (ø)
tests	86.46% <ø> (ø)

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[emersion]

LGTM with that nit fixed, but not tested! (feel free to resolve the discussion)

[SarahBellaha]

Tested, lgtm :)

[SharglutDev]

Lgtm and tested, nice improvement