Enum.new

helindbe and I had a chat in the slack today: https://puppetcommunity.slack.com/archives/C0W298S9G/p1614611196389300

The result of it is, that it would be nice to be able to `Enum.new`:

Boolean function parameter: Enum['apple', 'banana'](false) -> 'apple'

Integer function parameter: Enum['apple', 'banana', 'orange'](2) -> 'orange'

@Docs When the code is written, the `new` functions documentation needs to be updated. It has to list Enum.new and maybe show a little example. Similar to https://puppet.com/docs/puppet/latest/function.html#conversion-to-string