Add support for hiding enchantments via hide flags

[valaphee]

Description

This fixes #1852
by only sending an empty ench:[] tag for hidden enchantments, which will add the foil effect, which should not affect the items client behavior.

I didn't add hide flags for other items yet, because it wouldn't be possible to remove the additional data of fireworks etc. but other items, etc could be tested.

Testing

Has been tested on Waterfall connected to a 1.16 ViaVersion Paper server, with following command:
/minecraft:give @p acacia_button{Enchantments:[{id:aqua_affinity,lvl:1}],HideFlags:1} 1

[Camotoy]

I think this will break, at the very least, Curse of Binding.

[valaphee]

I think this will break, at the very least, Curse of Binding.

Yep this would generate ghost items, but this scenario is very unlikely, as it also isn't a thing that can be done as survival playing player, or in normal circumstances.

But I would support empty ench tags, which also gives the item the foil effect in Java and Bedrock Edition, and the stored ench additionai hide flag.

[Camotoy]

I'd rather not intentionally introduce a bug if we can help it... Maybe we don't check the hidden flag if Curse of Binding is present?

[valaphee]

I'd rather not intentionally introduce a bug if we can help it... Maybe we don't check the hidden flag if Curse of Binding is present?

Wouldn't do that, because then I would also have to exempt aqua affinity, frost walker, efficiency, etc. or it won't work.
or we only allow hiding unsafe enchantments, like enchantments on an acacia button.

For now I'll also revert hiding StoredEnchantments, because anvil also seems to be affected to not work anymore with hidden enchantments.

(In my commit I also changed the order of enchantments and storedenchantments, because this is how it will be processed in Java Edition, checked the source code for 1.19; and only enchantments, will always add an ench-Tag, even when empty)

[Camotoy]

Are the current changes actually beneficial to us in any way?

[valaphee]

When there are 0 enchantments, it will still add the ench Tag, which would allow same behavior as Java Edition, and a way to create the foil effect without showing enchantments
(it will not be added when StoredEnchantments is used (also like Vanilla Java Edition))