(#9617) Add a red-black tree map

This class is from Kanwei Li's algorithms gem, found at:

https://github.com/kanwei/algorithms

The only modifications are:

• renamed the class and nested it under the Puppet module
• removed a usage of Stack (from the algorithms gem) and replaced it with an Array
• added a check for has_key? before deleting
• added a #to_hash method, to aid in testing

Paired-With: Josh Cooper <josh@puppetlabs.com>