Remove unused type, add some @ApiStatus.Internal annotations

Author: Gegy

src/main/java/xyz/nucleoid/fantasy/util/FilteredRegistry.java

@@ -1,8 +1,11 @@
 package xyz.nucleoid.fantasy.util;
 
+import org.jetbrains.annotations.ApiStatus;
+
 import java.util.Collection;
 import java.util.Iterator;
 
+@ApiStatus.Internal
 public final class SafeIterator<T> implements Iterator<T> {
     private final Object[] values;
     private int index = 0;

src/main/java/xyz/nucleoid/fantasy/util/SafeIterator.java

@@ -3,8 +3,10 @@
 import net.minecraft.server.WorldGenerationProgressListener;
 import net.minecraft.util.math.ChunkPos;
 import net.minecraft.world.chunk.ChunkStatus;
+import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.Nullable;
 
+@ApiStatus.Internal
 public final class VoidWorldProgressListener implements WorldGenerationProgressListener {
     public static final VoidWorldProgressListener INSTANCE = new VoidWorldProgressListener();