Rethink how the Windows XP toolkit installs because the Chocolatey
installer(s) changed and broke the SIMH CI/CD build. Revert to a
previous strategy that updates the GH Windows runner image in-place with
Microsoft's vswhere and vs_installer tools.
There's some Grey Magic in how this is done, with some adapted
PowerShell code from the Chocolately PS scripts. The upshot is that
vs_installer spawns a subprocess to do the actual install, but there's
now way to get vs_installer to actually wait for that subprocess to
complete. So, the script has to look for the installer subprocesses and
poll-wait for them to finish.
* CMake build infrastructure
The squashed commit that builds and packages releases for the SIMH
simulator suite with CMake, version 3.14 or newer.
See README-CMake.md for documentation.
