Add a basic high-level wrapper over some of the Assimp APIs

[Perksey]

In our current 2.0 Assimp bindings we only expose 1:1 native bindings which are generated by our BuildTools generator. This is good, however it isn't very user friendly as it involves a lot of usage of unsafe and other native paradigms that aren't easy for beginners (you can see an example of it being used here and it's not as pretty as it could be)

Similar to assimp.net, we'd like to expose a higher-level managed wrapper on top of our low-level bindings so that it's easier to use and easy for people who've never used Assimp before to pick up. This could be done in steps, for example in one PR laying out an API surface, and slowly implementing it in subsequent PRs.

If you have any further questions feel free to join our Discord server - we're pretty much always active there.

[Perksey]

Bringing this back for this year's Hacktoberfest as well. This doesn't require much foreknowledge of Silk.NET's internals - this issue is mostly for building a C# API similar to Assimp's C++ API on top of Assimp's C API which we bind to automatically today. This can be C#-y and user-friendly 😄