Add get/setUpgrade to IPocketAccess

We have similar methods in ITurtleAccess, so makes sense for them to be
here too.

projects/common-api/src/main/java/dan200/computercraft/api/pocket/IPocketAccess.java

@@ -6,10 +6,12 @@ package dan200.computercraft.api.pocket;
 
 import dan200.computercraft.api.peripheral.IPeripheral;
 import dan200.computercraft.api.upgrades.UpgradeBase;
+import dan200.computercraft.api.upgrades.UpgradeData;
 import net.minecraft.nbt.CompoundTag;
 import net.minecraft.resources.ResourceLocation;
 import net.minecraft.world.entity.Entity;
 import net.minecraft.world.item.ItemStack;
+import org.jetbrains.annotations.ApiStatus;
 
 import javax.annotation.Nullable;
 import java.util.Map;
@@ -17,6 +19,7 @@ import java.util.Map;
 /**
  * Wrapper class for pocket computers.
  */
+@ApiStatus.NonExtendable
 public interface IPocketAccess {
     /**
      * Gets the entity holding this item.
@@ -64,6 +67,26 @@ public interface IPocketAccess {
      */
     void setLight(int colour);
 
+    /**
+     * Get the currently equipped upgrade.
+     *
+     * @return The currently equipped upgrade.
+     * @see #getUpgradeNBTData()
+     * @see #setUpgrade(UpgradeData)
+     */
+    @Nullable
+    UpgradeData<IPocketUpgrade> getUpgrade();
+
+    /**
+     * Set the upgrade for this pocket computer, also updating the item stack.
+     * <p>
+     * Note this method is not thread safe - it must be called from the server thread.
+     *
+     * @param upgrade The new upgrade to set it to, may be {@code null}.
+     * @see #getUpgrade()
+     */
+    void setUpgrade(@Nullable UpgradeData<IPocketUpgrade> upgrade);
+
     /**
      * Get the upgrade-specific NBT.
      * <p>
@@ -73,6 +96,7 @@ public interface IPocketAccess {
      * @see #updateUpgradeNBTData()
      * @see UpgradeBase#getUpgradeItem(CompoundTag)
      * @see UpgradeBase#getUpgradeData(ItemStack)
+     * @see #getUpgrade()
      */
     CompoundTag getUpgradeNBTData();