Migrate nullability annotations to jSpecify

Mojang has done that, we don't need 3 different sets of annotations

src/main/java/carpet/script/utils/AppStoreManager.java

@@ -34,7 +34,7 @@ import java.util.stream.Collectors;
 
 import org.apache.commons.io.IOUtils;
 
-import javax.annotation.Nullable;
+import org.jspecify.annotations.Nullable;
 
 /**
  * A class used to save scarpet app store scripts to disk

src/main/java/carpet/script/utils/FeatureGenerator.java

@@ -63,7 +63,7 @@ import net.minecraft.world.level.levelgen.structure.placement.StructurePlacement
 import net.minecraft.world.level.levelgen.structure.structures.JigsawStructure;
 import net.minecraft.world.level.levelgen.structure.templatesystem.StructureProcessorList;
 
-import javax.annotation.Nullable;
+import org.jspecify.annotations.Nullable;
 
 public class FeatureGenerator
 {

src/main/java/carpet/script/utils/GlocalFlag.java

@@ -1,6 +1,6 @@
 package carpet.script.utils;
 
-import javax.annotation.Nullable;
+import org.jspecify.annotations.Nullable;
 import java.util.function.Supplier;
 
 public class GlocalFlag extends ThreadLocal<Boolean>

src/main/java/carpet/script/utils/ParticleParser.java

@@ -6,7 +6,7 @@ import net.minecraft.commands.arguments.ParticleArgument;
 import net.minecraft.core.RegistryAccess;
 import net.minecraft.core.particles.ParticleOptions;
 
-import javax.annotation.Nullable;
+import org.jspecify.annotations.Nullable;
 import java.util.HashMap;
 import java.util.Map;
 

src/main/java/carpet/script/utils/ShapeDispatcher.java

@@ -57,7 +57,7 @@ import net.minecraft.world.level.block.Block;
 import net.minecraft.world.level.block.state.BlockState;
 import net.minecraft.world.phys.Vec3;
 
-import javax.annotation.Nullable;
+import org.jspecify.annotations.Nullable;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;

src/main/java/carpet/script/utils/WorldTools.java

@@ -34,7 +34,7 @@ import net.minecraft.world.level.levelgen.WorldGenSettings;
 import net.minecraft.world.level.storage.DerivedLevelData;
 import net.minecraft.world.level.storage.ServerLevelData;
 
-import javax.annotation.Nullable;
+import org.jspecify.annotations.Nullable;
 import java.io.IOException;
 import java.nio.file.Path;
 import java.util.List;

src/main/java/carpet/script/utils/shapes/ShapeDirection.java

@@ -1,6 +1,6 @@
 package carpet.script.utils.shapes;
 
-import javax.annotation.Nullable;
+import org.jspecify.annotations.Nullable;
 import java.util.Locale;
 
 public enum ShapeDirection