Add LoggingHelper to log deprecation messages

Towards #2533 (closed), here we add a LoggingHelper that can log and then summarise recommendations at the end of the chef run. We're focusing on deprecations first, action items and summarisation of failed converges may follow.

Sample output:

[...]
Running handlers:
Running handlers complete
Chef Client finished, 7/493 resources updated in 39 seconds
Deprecations:
Your git_data_dir settings are deprecated.
Please update it to the following:

git_data_dirs({
  "default": {
    "path": "/var/opt/gitlab/git-data"
  }
})

Please refer to https://docs.gitlab.com/omnibus/settings/configuration.html#storing-git-data-in-an-alternative-directory for updated documentation.
gitlab Reconfigured!