Improved multiverse regen

[pjindras]

Describe the feature

Hello, it would be very nice, if it was possible to keep paper config files, after /mv regen command, my server automatically regenerates nether after 30 days, but it also removes all world config options, including antixray in paper world config etc...

If it was possible to regen only the world but save the config files, it would be a great improvement.

How is the feature useful to all Multiverse users?

If someone has improved optimizations in world config, they could be kept.

Agreements

• [X] I have searched for and ensured there isn't already an open issue regarding this.