feat: Adjust freeimage to all platforms

[Jklawreszuk]

PR Details

This PR adjust FreeImage loading for macos and linux distributions (these operating systems load this dependency from packages).
From now, FreeImage is handling image files instead of DirectXTex library (LoadWICFile method is only available for Windows) .

Types of changes

• Docs change / refactoring / dependency upgrade - Additional dependency to install
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• My change requires a change to the documentation.
• I have added tests to cover my changes.
• All new and existing tests passed.
• I have built and run the editor to try this change out.

[Eideren]

TC is complaining, might need to adjust those texture extensions you removed to get loaded by freeimage instead ?
https://teamcity.stride3d.net/buildConfiguration/Engine_Tests_WindowsSimple/25548?hideTestsFromDependencies=false&hideProblemsFromDependencies=false&expandBuildDeploymentsSection=false&expandPull+Request+Details=true&expandBuildChangesSection=true&expandBuildProblemsSection=true

[Jklawreszuk]

@Eideren Glad the tests caught the error 😅 According to the documentation, it seems that FreeImage has dedicated both Unicode and Non-Unicode methods that should be used accordingly on Windows or Unix systems.

FreeImage 3.18.0 documentation FreeImage_LoadU
Note that this function only works on MS Windows operating systems. On other systems, the
function does nothing and returns NULL.

[Jklawreszuk]

I started looking for inspiration and it looks like our friends at Monogame fixed this by using appropriate method depending on the system. I will try to go in this direction
Monogame :

[DllImport(NativeLibName, CharSet = CharSet.Unicode, EntryPoint = "FreeImage_LoadU")]
      public static extern IntPtr LoadU(FREE_IMAGE_FORMAT fif, string filename, int flags);

      [DllImport(NativeLibName, EntryPoint = "FreeImage_Load")]
      public static extern IntPtr LoadS(FREE_IMAGE_FORMAT fif, string filename, int flags);

      public static IntPtr Load(FREE_IMAGE_FORMAT fif, string filename, int flags)
      {
          if (CurrentPlatform.OS == OS.Windows)
              return LoadU(fif, filename, flags);
          else
              return LoadS(fif, filename, flags);
      }

[Jklawreszuk]

Done! @Eideren, Could you try to run tests again?

[Eideren]

We have a certificate issue right now that xen is looking into, I'll get back to you once it's done :)

[Eideren]

Thanks !