[Feature]: Enderchest slot

[FatPorpoise]

What is the new feature or improvement?

I've been using your mod for a while now alongside Easy Shulker Boxes and I've found myself taking shulker boxes out and putting them inside ender chest via that mod a lot (while having ender chest in shulker backpack or player inventory),
so I started looking for a mod like yours but with ender chests, unfortunately I couldn't find it.
Seems like it'd be very similar to what you had already created and It'd be a really nice extension to what this mod already does.