In order to make it easier for Copilot to help us in this repository, it would be good to be able to partially build this repository on Linux.

Building any native code (C/C++/Objective-C) would not be possible (because there's no Xcode on Linux), but downloading .NET itself + building managed code should be possible.

Goal: successfully run make from the root directory, and it will iterate into the builds directory (to download .NET), and then iterate into the src directory (to build managed code).