Restricted Flying

A little update to throw an error if playing on 1.21.5 and above.

No new changes

Fixes critical bug when gliding on 1.21.5

• Fixed a bug where the config wouldn't be loaded on startup
• New command: /nofly config show to show all dimensions in the allowed list
• When doing /nofly config add <dimension>, it will now suggest dimensions that are in the list of dimensions

Initial upload