Block specific items/blocks into enderchest/containers using Blacklist

### The Problem

I want to block being able to put shulkers into enderchests.

The perfect solution would be to use the blacklist feature of WorldGuard.
https://worldguard.enginehub.org/en/latest/blacklist/

Even better, if its just adapted to allow blocking putting X item into Y container, then we can have all sorts of unique possabilities for gameplay.

### A Solution

New event for blacklist, something like `enderchest-in` and `enderchest-out` (and do the same for all containers)

Then it would be something like
```
[BLACK_SHULKER_BOX, BLUE_SHULKER_BOX]
enderchest-in=deny,tell
```

### Alternatives

_No response_

### Anything Else?

_No response_