Add New Function, Convert to PDK 2.2

[greatflyingsteve]

We needed a function which when given two IP addresses, would return the size of the smallest set of contiguous addresses that contains both arguments. Feed it a starting IP and ending IP, and it returns you the size of that range. There's so much other great, useful stuff in here that it seemed like a pretty natural addition to contribute.

I've also re-fit the module with PDK bindings, which are the first two commits in this PR and about 95% of the total change. If you JUST look at my third commit, that's the only new actual code. Of note for the PDK stuff:

• All the unit tests still pass exactly as they originally did, tested as far back as Puppet v5.5.22 and as late as v7.9.0
• The only two rubocop complaints remaining are about missing top-level module and class documentation comments
• Nothing was otherwise changed until that third commit.

Steps to arrive at the first two commits were:

pdk convert
pdk validate ruby -a

Then go into each function definition and remove the error assignment to e because rubocop was unhappy about it, since e was never referenced again
Increment the module version in metadata.json from 2.2.0 to 2.2.1

For the new work in the 3rd commit, I added the function underpinnings in ip.rb and the parser function, then incremented the module version to 2.3.0.

Also, pretty please tag the 2.2.1 and 2.3.0 commits appropriately - I don't know of a way to include tags in a PR.

[greatflyingsteve]

@inkblot if you have a moment