Adding valueless tags to PersistentDataContainer

Is your feature request related to a problem?

When using a PersistentDataContainer to hold Booleans, you can basically treat the key existing as the boolean value. So, I figured why not add a way to make a valueless tag so I can just store a NamespacedKey on a PDC and check if it exists.

Describe the solution you'd like.

A new function could be added to PersistentDataContainer
void tag(NamespacedKey key)
All it'd do is run set(key, PersistentDataType.BOOLEAN, false) or something.

Then, you can use PersistentDataContainerView#has and PersistentDataContainer#remove like you would now.

Describe alternatives you've considered.

Alternatively, multiple functions could be added so that tags don't interfere with any other data stored on the entity. Adding a list of strings to the NBT data would do this fine.

Three functions would be added to the API (I'm a little unsure of the internal PDC workings, sorry)

Inside PersistentDataContainerView:

• boolean hasTag(NamespacedKey key)

Inside PersistentDataContainer:

• void tag(NamespacedKey key)
• void untag(NamespacedKey key)

Alternatively, it could be addTag and removeTag.
These could be stored in a list attached to the NBT data, or it could assign a value of 0 internally.

Other

No response

Start with the PersistentDataContainer and PersistentDataContainerView API entry points named in the issue, then compare the existing set, has, and remove behavior. Done means reaching a settled design for valueless tags, including their interaction with existing data, and documenting or implementing the proposed API consistently.