support agent on windows

[abe-winter]

What changed

• installer support
  • old agent.bat (can ditch this at some point)
  • YML workflow to build msi
  • .wxs file for MSI
• utils
  • config.go: add two Disabled() getters to always disable some subsystems on windows (regardless of config)
  • utils.go: path setup, factor our checkPathOwner, auto-add .exe extension, fix some file handling errors, do netsh
  • make Kill and SyncFS platform-dependent
  • add KillTree
• main.go
  • factor out big chunks that don't work on win yet: runPlatformProvisioning, waitOnline
  • add main_windows.go which manages a windows service

Why

Support agent on windows

Manual testing

• on windows:
  • test start / stop (including RDK module processes)
  • test upgrading RDK + agent
• test to make sure linux hasn't been broken