Clipped pregen prefetch

- Limited chunk prefetch rings to the windows a bounded pregeneration still needs
- Forwarded pregeneration region bounds from the async, medieval and modded methods
- Restored unclipped prefetch when the pregeneration closes
- Added a runtime test for clipped and restored prefetch

adapters/modded-common/src/main/java/art/arcane/iris/modded/command/ModdedPregenMethod.java

@@ -348,6 +348,11 @@ public final class ModdedPregenMethod implements PregeneratorMethod {
         return false;
     }
 
+    @Override
+    public void onRegionBounds(int minRegionX, int minRegionZ, int maxRegionX, int maxRegionZ) {
+        hydrology.bound(minRegionX, minRegionZ, maxRegionX, maxRegionZ);
+    }
+
     @Override
     public void onRegionsAhead(List<long[]> regions) {
         if (!closing.get()) {