Add option to create self-contained trimming repro

We often get issues like https://github.com/dotnet/runtime/issues/75802 which are hard to reproduce without a very specific build setup. It would be helpful if we had an officially supported option that would create a self-contained repro (with all input assemblies and the linker commandn-line options) that can then be shared easily.

@vitek-karas I know you have created a tool like this - what would it take to make that officially supported?