FOMOD installer fixes

[Al12rs]

Changes:

• Fix FOMOD installer failing to show images present in archive #860
• Fix Fomod installer doesn't show images when switching from option without image to option with. #864
• Fix Fomod installer show option details when pressing checkbox #865
• Fix [Fomod installer] Fix styling to join borders of description section #866
• Improved Fomod progress bar accuracy when there are few steps or hidden steps.
• Fixed tests to detect failures in loading fomod images.
• Enabled Multithreading when extracting archives with 7zip.

EDIT: further changes after reviewing with Design:

• Switched highlighted option description and image, so that description would always be visible.
• Various padding/spacing fixes.
• Fix Caps on Finish button.
• Fix auto scrolling to last option when new step is loaded.

[codecov-commenter]

Codecov Report

Attention: 26 lines in your changes are missing coverage. Please review.

Comparison is base (23a4b1d) 60.37% compared to head (241d788) 60.33%.
Report is 2 commits behind head on main.

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Additional details and impacted files

@@            Coverage Diff             @@
##             main     #867      +/-   ##
==========================================
- Coverage   60.37%   60.33%   -0.05%     
==========================================
  Files         592      592              
  Lines       18375    18397      +22     
  Branches     1424     1427       +3     
==========================================
+ Hits        11094    11099       +5     
- Misses       6945     6963      +18     
+ Partials      336      335       -1     

Flag	Coverage Δ
Linux	59.69% <13.33%> (-0.03%)	⬇️
Windows	59.56% <13.33%> (-0.03%)	⬇️
clean_environment_tests	60.31% <13.33%> (-0.05%)	⬇️
networking_tests	?

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
...Mods.FileExtractor/Extractors/SevenZipExtractor.cs	73.68% <100.00%> (ø)
src/Games/NexusMods.Games.FOMOD/FomodAnalyzer.cs	95.38% <66.66%> (+3.32%)	⬆️
...s.Common/GuidedInstaller/GuidedInstallationStep.cs	42.85% <0.00%> (-7.15%)	⬇️
...es.FOMOD.UI/Group/GuidedInstallerGroupViewModel.cs	0.00% <0.00%> (ø)
.../NexusMods.Games.FOMOD/CoreDelegates/UiDelegate.cs	5.55% <7.69%> (-0.19%)	⬇️

... and 6 files with indirect coverage changes

[erri120]

See comments for changes.

[github-actions]

This PR conflicts with main. You need to rebase the PR before it can be merged.

[github-actions]

This PR doesn't conflict with main anymore. It can be merged after all status checks have passed and it has been reviewed.