Adapt code for Google Cloud Storage

I made the clone and initial changes from code originally from https://github.com/unasuke/s3_cache_store

Need help to actually implement the Rails cache store for Google Cloud Storage.

Documentation: 
https://guides.rubyonrails.org/caching_with_rails.html
https://guides.rubyonrails.org/caching_with_rails.html#activesupport-cache-store