Check PlatformSupport on Linux

[chrisyarbrough]

We need to test the utility on Linux (ubuntu is the distribution officially supported by Unity).

Additionally, we should verify the hardcoded, platform specific things in:

https://github.com/chrisyarbrough/UnityCommandLineLauncher/blob/main/dotnet/ucll/Utility/PlatformSupport.cs

[chrisyarbrough]

I had good success testing Windows support via UTM, but the Linux ubuntu VM from the marketplace crashed on my system.

[chrisyarbrough]

Unity's release notes mention a bug fix on their side which we might to check in our logic to detect the Unity Hub location in UCLL:

Editor: Fixed Unity Editor not detecting Unity Hub installation on Linux. The Editor now correctly checks both user-local (~/.local/share/applications/) and system-wide (/usr/share/applications/) locations for the Hub desktop file, and properly respects the XDG_DATA_HOME environment variable. (UUM-96606)