VS: Honor VS_SETTINGS property on all sources
VS_SETTINGS source file property added by !4498 (merged) only applies to "extra" sources.
I need it to apply to regular source/header files.
The immediate need was to set "ExcludedFromBuild" using a generator-expression.
HEADER_FILE_ONLY doesn't support generator-expressions, so it wasn't an option.
VS_SETTINGS only affects the Visual Studio generators, so this should (hopefully) be an easy approval.