VS: Only link cs files when they're not in binary dir

When `*.cs` files are provided, do not generate a `<Link>` element in
the `.csproj` project if those files are descendants of
`CMAKE_CURRENT_BINARY_DIR`. This comparison happens for each file.
Status Job ID Name Coverage
  External
passed ghostflow-branch-check-master

passed ghostflow-commit-check

passed ghostflow-stager