Information about installed MSVC instances are stored in `state.json` files within a `Packages/_Instances` directory. The default location for this is `%PROGRAMDATA%\Microsoft\VisualStudio\Packages\_Instances`. However, it is possible for the Packages directory to be put somewhere else. In that case, the registry value `HKLM\SOFTWARE\Microsoft\VisualStudio\Setup\CachePath` is set and contains the path to the Packages directory.

Previously, WindowsSdk did not check that registry value. After this commit, the registry value `HKLM\SOFTWARE\Microsoft\VisualStudio\Setup\CachePath` is checked first, which matches what ISetupEnumInstances does (according to a Procmon log).