Adds support for OSX in the App

[halgari]

The app will run in debug mode, with the debugger running. What works:

• Can find games in Steam
• Can open the UI
• Tests Pass
• Running Games
• [ ] Downloading files (need NXM handler) Support nxm:// links on OSX #962
• [ ] Updating the app (needs a release first) Support MacOS updating #964
• Run it in release mode (Single process code seems broken on OSX) (fixed)

[codecov-commenter]

Codecov Report

Attention: 62 lines in your changes are missing coverage. Please review.

Comparison is base (96e3f76) 55.33% compared to head (3651332) 58.61%.
Report is 14 commits behind head on main.

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Additional details and impacted files

@@            Coverage Diff             @@
##             main     #877      +/-   ##
==========================================
+ Coverage   55.33%   58.61%   +3.27%     
==========================================
  Files         620      632      +12     
  Lines       20058    20326     +268     
  Branches     1544     1564      +20     
==========================================
+ Hits        11100    11914     +814     
+ Misses       8614     8050     -564     
- Partials      344      362      +18     

Flag	Coverage Δ
Linux	57.85% <14.81%> (+3.12%)	⬆️
Windows	57.79% <11.11%> (+3.20%)	⬆️
clean_environment_tests	58.59% <23.45%> (+3.28%)	⬆️
macOS	57.25% <19.75%> (?)

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

Files	Coverage Δ
...stractions.FileExtractor/IFileExtractorSettings.cs	66.66% <100.00%> (ø)
...Mods.FileExtractor/Extractors/SevenZipExtractor.cs	74.33% <ø> (-0.45%)	⬇️
src/NexusMods.App/AppConfig.cs	72.58% <100.00%> (ø)
src/NexusMods.CrossPlatform/Services.cs	100.00% <100.00%> (+5.26%)	⬆️
src/NexusMods.DataModel/IDataModelSettings.cs	60.86% <100.00%> (ø)
src/NexusMods.DataModel/SqliteDataStore.cs	77.89% <100.00%> (+0.23%)	⬆️
src/NexusMods.StandardGameLocators/Services.cs	79.54% <100.00%> (+2.04%)	⬆️
src/NexusMods.App/Services.cs	83.95% <0.00%> (ø)
src/NexusMods.App/Startup.cs	48.00% <0.00%> (-4.18%)	⬇️
...rm/ProtocolRegistration/ProtocolRegistrationOSX.cs	0.00% <0.00%> (ø)
... and 3 more

... and 73 files with indirect coverage changes

[erri120]

See comments.

[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.

[halgari]

This should be good to merge. I had to implement some code to make sure the UI always runs on the main thread (the thread that calls Main. Turns out that the fact that this has worked this long is a side effect of our OS implementations not a design feature of Avalonia. AvaloniaUI/Avalonia#12554 Avalonia has no plans to lift this restriction.

With that we're good to go for OSX support. I need to get in NXM link support, and figure out release/updating but I'll file other issues for that

handled

[erri120]

See comments.