Produce object archive as intermediate build step

[EggAllocationService]

It would be helpful for the C# wrapper if it could produce an object archive (.a file) as part of the build process. The use case is that the C# wrapper requires another native function to properly call variadic functions on Apple Silicon and right now that's included in a separate dynamic library.

If we could produce some intermediate file as well, the C# wrapper Makefile could create a seperate libmapper.dylib while packaging for nuget that bundles the native wrapper, so at runtime only one .dylib is needed.