Enable arcade -sign functionality across aspnetcore's build

[mmitche]

aspnetcore's signing functionality depends somewhat on shuttling bits from Linux/Mac to Windows. As arcade gets proper support for -sign on Mac and Linux, we should alter aspnetcore to be more 'vertical'. No shuttling around. This has benefits for aspnetcore in the short term, allows arcade to prove out its non-Windows signing functionality, and sets up aspnetcore builds to work well in signed VMR builds.

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[mmitche]

@ellahathaway

[ellahathaway]

FYI this is currently blocked on a MicroBuild issue: https://dev.azure.com/devdiv/DevDiv/_workitems/edit/2270151

[wtgodbe]

Awesome! Let me know if there's anything I can do to help