Support .dSYMs from NuGets / binding libraries

Right now we don't handle dSYM directories for user frameworks in any way, however in the past we used to run `dsymutil` on user frameworks in order to create a corresponding dSYM.

Unfortunately this wasn't not a good idea, because very often third-party user frameworks are shipped optimized/stripped of debug info, and running `dsymutil` on such a framework doesn't produce anything helpful (and we'd be blamed). Ideally third-party user frameworks should ship with a .dSYM directory as well.

This issue is to handle third-party user frameworks that ship with .dSYM directory better by:

* [ ] Adding support for embedding .dSYM directories in binding libraries (both compressed and in the sidecar).
* xcframeworks seems to support embedding dSYMs directly, which simplifies things a bit, since most of the existing logic should just work: https://msolarana.netlify.app/2021/01/12/embedding-debug-symbols-in-xcframeworks/
* [ ] Copying .dSYM directories we find from binding projects or NuGets next to other dSYMs we create during the build.

Ref: https://github.com/xamarin/xamarin-macios/issues/14598