[jpenilla]

Fires ServerChunkEvents.CHUNK_LOAD, CHUNK_GENERATE and CHUNK_UNLOAD from NeoForge's ChunkEvent.Load/Unload (server levels only) instead of the vanilla injections in ChunkStatusTasks and ChunkMap. Mods that replace vanilla's chunk system and post NeoForge's events themselves, such as Moonrise, then get the Fabric events too. See #302.

• ChunkEvent.Load is posted at the end of the same ChunkStatusTasks.full lambda the old injection targeted, and isNewChunk() uses the same !(protoChunk instanceof ImposterProtoChunk) check as generated.
• ChunkMapMixin is removed. CHUNK_UNLOAD now fires after the chunk is saved, as NeoForge's ChunkEvent.Unload does, rather than before.
• The initial FULL_CHUNK_STATUS_CHANGE transitions are still fired from ChunkStatusTasksMixin; NeoForge has no equivalent event.

Tested on a 26.1.2 dedicated server by counting events for one chunk through generate, unload, reload and server stop:

	load / generate / unload / full status change
before, without Moonrise	2 / 1 / 2 / 12
after, without Moonrise	2 / 1 / 2 / 12
before, with Moonrise	0 / 0 / 0 / 0
after, with Moonrise	2 / 1 / 2 / 0

LoadedChunksCache tracks the chunk correctly in both "after" runs. Full status changes with Moonrise are left for Moonrise to handle.