(RE-15124) Implement DNS Plugins and Remove api v1 and v2

[yachub]

This implements plugable DNS plugins, similar to compute providers.

Relates to:

• (RE-15124) Decouple DNS Record Management into DNS Plugins vmpooler-provider-gce#21
• (RE-15124) Collect VMs IP for use with DNS Plugins vmpooler-provider-vsphere#29
• (RE-15124) Initial implementation vmpooler-dns-gcp#1

[e-gris]

Only comments on Ruby style or idiomatic usage. Feel free to take or ignore.

Also, generally, avoid method variables like name, Even the method comments have suggestions for better choices.

I've shown a few examples but didn't flag them all.

[e-gris]

Some more purely stylistic/maintainability comments; certainly ignorable for now. I called out just a couple of examples.

Nested 'ifs' and variable mutations are great places for bugs to hide and are often easily refactored into something more stable

[genebean]

So, I am only part of the way through, but it seems that this PR introduces breaking changes within the versioned API endpoint api/v2... that is not okay. Breaking changes need to be implemented as a new api version. I think what you are doing here api wise need to be done as part of api/v3. It is fine if you kill of the v1 and v2 endpoints as part of this work too.

[genebean]

Please don't merge until after squashing (I know you are working on it). Adding a label to ensure this.

[yachub]

Just working on squashing commits now