Add dots backup

[ulises-jeremias]

As a user of the dotfiles installer I want to have the option of creating a backup of my current dotfiles.

The script should be named dots-backup and it should be placed at the root level of this repository and installed behind this line here.

Technical Notes

• The script should define a comment with the usage following this pattern here
• The script should import the args parser as here
• It should use the argument --dotfiles-dir (the content will be on variable dotfiles_dir) to look for the actual configuration.
• Once it finishes, it should print the path to the created .tar.gz file containing the backup 👌🏻

Reach out to @ulises-jeremias for more usage details or any other related topic 😃

[ulises-jeremias]

The backup script already exists. We just need to make it possible to rollback to a previous snapshot