Rework the nether #14

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

Currently all islands use one nether with a central spawn. While this allows for easy trading once players reach the nether it doesn't really feel like Skyblock.

Describe the solution you'd like

Make it so each island gets its own portal spaces out by a couple hundred blocks in the nether so that players need to travel to each other. (Portals should spawn in the air on a small nether themed skyblock island)

Modify the nether generation so that it feels more like skyblock. This could be done by removing any generation of nether rack and maybe other blocks too (ores need to definitely be removed, the special biomes like crimson&warped forest, basalt deltas & soul sand stuff probably too) creating vast spaces of lava that need to be traversed posing a similar challenge to the normal skyblock but now in the nether. Fortresses and other structures should probably still generate.

We probably also want nether-specific challenges but that will be part of a separate issue, especially as people right now might have tons of nether stuff already so their value would be weird. Maybe only in a Season 2 with all new islands?

Describe alternatives you've considered

One nether per island. This would be pretty boring in a multiplayer server though and increase the space needed per island massively.

Additional context

No response