(HI-273) Support bundler workflow on windows x64

Previously the Gemfile contained windows gem dependencies copy and
pasted from elsewhere.

Hiera only explicitly depends on the `win32-dir` gem to resolve
its data directory on windows, e.g. C:\ProgramData. As such the
Gemfile is updated to include that dependency.

The dependency is also specified in the project_data.yaml file used
when creating platform specific gems.