Merge branch 'mc-1.16.x' into mc-1.18.x

I dare say there's going to be some bugs with this. I was as careful as
I could be, but yikes it was nasty.

src/test/java/dan200/computercraft/support/FakeContainer.java

@@ -0,0 +1,25 @@
+/*
+ * This file is part of ComputerCraft - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2022. Do not distribute without permission.
+ * Send enquiries to dratcliffe@gmail.com
+ */
+package dan200.computercraft.support;
+
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.inventory.AbstractContainerMenu;
+
+import javax.annotation.Nonnull;
+
+public class FakeContainer extends AbstractContainerMenu
+{
+    public FakeContainer()
+    {
+        super( null, 0 );
+    }
+
+    @Override
+    public boolean stillValid( @Nonnull Player player )
+    {
+        return true;
+    }
+}