QtVSTools in windows docker with VS Build Tools 2019

Hello,

As we recently introduced a build docker image based on servercore:1809 for building our C++/Qt applications.

For the projects to build successfully, the props, targets etc. introduced by Qt VS tools are required in the docker environment.

Currently as workaround, we have to copy the contents of `$QtMsBuild` from a PC with working VS2019/Qt installation into the docker image and add some registry keys to allow to the Qt VS tools to resolve Qt-specific environment variables.

e.g.

[HKEY_CURRENT_USER\Software\Digia\Versions\msvc2019_64]
"InstallDir"="C:\\Qt\\5.15.2
msvc2019_64"

Is there another way to streamline this? Is there any alternative (silent?) way to install the VS extension into the docker image to avoid copying machine specific files? Is this use case covered by the docs?