Api for deserializing items with partially invalid data

[RodneyMKay]

Summary

This PR introduces a safe deserialization method for ItemStack to handle items containing unknown data without throwing exceptions, ensuring parity with vanilla behavior for inventory handling.

Background

In vanilla Minecraft, when a player joins with an item containing enchantments from a missing namespace (e.g., customenchant:autosmelt), the server logs a warning and allows the player to keep the item with the invalid enchantment stripped. Currently, ItemStack.deserializeBytes throws a hard error in these cases, providing no way to access this partial result.

Of course, ideally, plugin developers would implement their own data versioning system, where data from things like custom enchantments is migrated to a valid format automatically, but that is more complex to support. Allowing access to the vanilla-type behavior should be good enough for now.

This PR

A new method, deserializeBytesSafely, has been added alongside the standard deserializeBytes. This method returns a DataResult instead of throwing an exception, allowing the API to provide a partial result even when specific components fail to deserialize.

DataResult API

The DataResult API is implemented as a sealed class hierarchy, which is easy for pattern matching and restricts invalid usages. However, I also included several convenience methods on the top-level interface to simplify common operations. Other than that, it mimics the semantics of the com.mojang.serialization.DataResult from Mojang's DataFixerUpper.

This is what the API looks like in a simplified fashion:

public sealed interface DataResult<R> {
    record Success<R>(
        R result
    ) implements DataResult<R> {}

    record ErrorWithPartialResult<R>(
        String errorMessage,
        R partialResult
    ) implements DataResult<R> {}

    record Error<R>(
        String errorMessage
    ) implements DataResult<R> {}
    
    Optional<R> getResult();

    Optional<R> getPartialResult();

    Optional<String> getErrorMessage();

    R resultOrThrow();

    R partialResultOrThrow();
}