Add a git hook that generates in each commit a file whose name matches `RubocopAnalysis::CLI::DEFAULT_FILE_PATH`

The project currently uses a default file name to run the rubocop analysis on it.

The git hook added here will make any new commit auto generate that rubocop file with the list of
offended files and their offenses in JSON format. This way, anyone who clones this repo will have
a default JSON file to test this project without the need to generate the file themselves.