*** Engine updates and fixes

- Update PowerShell to use `2.0.6` dotnet core runtime and packages.

*** Build and Packaging Improvements

- Add Ubuntu build without AppImage (#6380)
- Add scripts to set and or update the release tag in VSTS (#6107)
- Fix DSC Configuration compilation (#6225)
- Fix errors in `Start-PSBootStrap` during release builds (#6159)
- Fix spelling failures in CI (#6191)
- Use PowerShell `windowsservercore` Docker image for release builds (#6226)
- Use `ADD` instead of `Invoke-WebRequest` in `nanoserver` Docker file (#6255)
- When doing daily/test build in a non-release branch use the branch name as the preview name (#6355)
- Add Environment Variable override of telemetry (#6063) (Thanks @diddledan!)
- Build: Remove two unneeded lines from 'Invoke-AppveyorFinish' (#6344)
- MSI: Refactor `New-MsiPackage` into `packaging.psm1`
  and various fixes to enable patching
  (#5871, #6221, #6254, #6303, #6356, #6208, #6334, #6379, #6094, #6192)
- MSI: Use HKLM instead of HKCU registry keys since the current installation scope is perMachine. (#5915) (Thanks @bergmeister!)