Migrate to a modern .NET version (8.0)

[energydrink02]

I have created a branch where IndustrialPark and its subprojects have been successfully updated to .NET 8.0. This also includes following additional changes:

1. Updated Dependencies:

• Updated SharpDX.Desktop to the latest compatible version.
• Updated AssimpNet to the latest compatible version (fixes DAE vertex colours are incorrect due to an Assimp.net bug #54 and adds more features like *.fbx export)

2. Codebase Improvements:
   • Replaced obsolete functions with their modern equivalents.

Testing:
I have tested the updated branch and ensured that all existing tests pass successfully. However, additional testing would be beneficial to ensure full compatibility.

[ItsPepperpot]

Thanks for doing this. .NET 8.0 would be a good step towards having a cross-platform IP version. Also, would make running the tests easier since we can use dotnet instead of having to use a patched version of Microsoft's VSTest action (it's been broken for two months but they haven't fixed it :V)

Would also be nice to see that Assimp bug fixed. The latest version is a prerelease so hopefully there's no new bugs in it - that would require some testing.

Possible downsides are:

• Application would no longer be compatible with Windows 7 SP1+, 8, 8.1 or 10 (before update 1607). However, most people using the application are probably on later versions of Windows 10, or Windows 11 so this shouldn't affect most users.
• The Windows forms designer doesn't currently work in JetBrains Rider which is what I use. (It works for .NET Framework, but not .NET). They're working on getting it implemented apparently, but it won't be in Rider until after version 2024.2.

[ItsPepperpot]

There is actually a more recent fork of assimpnet:
https://github.com/StirlingLabs/Assimp.Net
https://www.nuget.org/packages/StirlingLabs.Assimp.Net/

Perhaps we could use that one instead.

[energydrink02]

Yea we should not target Windows 7/8 support and the Windows 10 update 1607 is from 2016 so that should be fine too.

The Assimp.Net package does target a newer version (5.2.5 vs. 5.0.0) but throws an error trying to import/export a model on my end: "The specified module could not be found. (0x8007007E)", even though the module (assimp.dll) does exist in the specified path.

Taking a look at this we should be fine, I think: https://learn.microsoft.com/en-us/dotnet/core/porting/
HeroesPowerPlant already switched to .NET 8 so we can take a look there too.

I would consider switching to .NET 8 after the next IP release anyway so waiting for a rider update is fine too.