VS: Find Visual Studio 2019 Build Tools
The VS 2019 Build Tools are not reported by the Visual Studio Installer
tool through the normal enumeration. Instead we must enumerate "all"
instances to see it. We already have logic to filter out instances that
do not have a compiler installed and also have the generator setting
CMAKE_GENERATOR_INSTANCE
to allow use of specific instances, so
enumerating all instances should be okay.
Fixes: #19241 (closed)
Topic-rename: vs2019-build-tools
Edited by Brad King