Enable NewCops up to a specific version of rubocop

[dgollahon]

Is your feature request related to a problem? Please describe.

I don't prefer to use NewCops: enable because I like finding out what cops are new and configuring them to my liking. That said, I end up with a ton of configuration that is redundant with the default config just to enable all the cops.

Describe the solution you'd like

I would like to be able to do something like NewCops: 1.50.0 where it will have the default behavior of enable/disable up until that version and then show me warnings for just what's new. That way I have a smaller/simpler config but I still opt-in as new versions are released.

Describe alternatives you've considered

The only other alternative I'm aware of is manually maintaining this like I'm currently doing.

Additional context

I'm not sure how this should interact with plugins. It might need multiple version entries or some way to configure separately.

I thought there was an issue around this from a long time ago but I can't find it so sorry if this ends up being a duplicate.

[bbatsov]

There's #8565 that got stuck for various reasons. Feel free to revive it.