Upgrade project files to SDK-style format compatible with dotnet

[adecler]

Issues addressed by this PR

Fixes #251

• The project files were still using the legacy .NET Framework project files and needed to be upgraded to SDK-style format compatible with dotnet.
• I have not upgraded the framework to netstandard2.0 as I was not confident this would be compatible for this repo and its dependencies.
• Finally, I have fixed compilation errors due to missing explicit casting for objects returned by GetDispInterfacePointerByEnum.

Tests

• Make sure the solution build with dotnet build
• Run your end of milestone testing procedure

Note on the need for explicit casting

The old .csproj explicitly set EmbedInteropTypes=True on the interop reference (confirmed in git). With the old project format (non-SDK, packages.config), the .NET Framework build toolchain's NoPIA (No Primary Interop Assembly) embedding mechanism was more permissive — it allowed implicit assignment from object to a COM interface type that was simultaneously being embedded into the consuming assembly, treating it as type-equivalent at the point of use. The compiler silently inserted the conversion.
The new SDK-style project format uses a stricter Roslyn integration. Even when EmbedInteropTypes=True is active (the default for Interop.* packages), it no longer permits that implicit object → specific COM interface coercion. It requires the cast to be written explicitly.

[adecler]

@BHoMBot check compliance

[bhombot-ci]

@adecler to confirm, the following actions are now queued:

• check code-compliance
• check documentation-compliance
• check project-compliance
• check branch-compliance
• check dataset-compliance
• check copyright-compliance

[adecler]

@BHoMBot check project-compliance
@BHoMBot check code-compliance
@BHoMBot check copyright-compliance
@BHoMBot check documentation-compliance

[bhombot-ci]

@adecler to confirm, the following actions are now queued:

• check project-compliance
• check code-compliance
• check copyright-compliance
• check documentation-compliance

[enarhi]

Unfortunately the adapter appears to be failing after building with the updated code. The error I receive is:

1. This component failed to run properly.
- Error: Could not load file or assembly 'Interop.RAMDATAACCESSLib, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'. The system cannot find the file specified.
- Occured in  BH.Adapter.RAM.RAMAdapter..ctor(String filePath, Boolean active)
     called from BH.UI.Base.Caller.Run(List`1 inputs)
- Are you sure you have the correct type of inputs? Check their description for more details.

I confirmed that building from develop with the same environment I do not receive this error, so it appears specific to the dotnet upgrades.