Feature/26.3 registries

[eclipseisoffline]

Summary of changes:

• GeyserHolderSets support heterogeneous NBT lists using text-serializer-nbt's implementation.
• JavaRegistryProvider now provides both Java registry and tag data, allowing tags to be used in gametests.
  • Is implemented by JavaRegistryTagCache in Geyser. RegistryCache and TagCache still exist, but are not used directly anymore.
• JavaRegistryLookup and JavaRegistryKey's get* methods now either return an optional or throw when an element is missing, enforcing safety. The exception notes the registry name and lookup details.
• SimpleJavaRegistry was reworked significantly:
  • It now keeps multiple maps for ID <-> entry, key <-> entry, and entry <-> ID/key lookups, reducing lookup time for all lookups except for ID -> entry (these lookups were previously done by iterating all entries, resulting in a performance penalty).
  • It now has a frozen and mutable state, and a RegistryEntryData can be unbound (unknown) before freezing (see Javadocs).
  • A new interface hierarchy has been created:
    • At the top there is JavaRegistryLookup providing simple access to one or more registry entries.
    • JavaRegistry extends JavaRegistryLookup with methods to iterate over the entire registry.
    • MutableJavaRegistry extends JavaRegistry and has a mutable and frozen state, and is implemented by SimpleJavaRegistry.
• Registries for Java blocks, items, and entity types are now kept in a new BuiltInJavaRegistries class, and use SimpleJavaRegistrys, which allows using the same ID/key/entry <-> ID/key/entry lookups as per-session registries, and allows a clean incorporation with per-session registries.
• Registry readers have been moved out of RegistryCache and into a new JavaRegistryReaders class, and a distinction has been made between readers that depend on the entry's key and those that do not (see Javadocs).
• Across the codebase, passing around GeyserSession just for registry access has been removed, preferring to pass the weakened JavaRegistryProvider instance instead.
• Most Java registry classes have been relocated to the org.geysermc.geyser.registry.java, except for the session-cache classes.
• GeyserHolderSet now has gametests.
• Item#javaIdentifier() (returning a string representation of the Key) has been removed, preferring to use Keys when possible instead.

All registry classes have received up-to-date Javadocs giving a thorough explanation of their inner workings and usage.

[onebeastchris]

Looks awesome! Don't have much to say tbh; structure wise i (without claude this time, heh) like this. Great to see more tests too 👀

[onebeastchris]

EntityDamageCause cause = JavaRegistries.DAMAGE_TYPE.get(session.javaRegistries(), packet.getSourceTypeId())
        .orElse(EntityDamageCause.OVERRIDE);

Don't see why we'd need the optional :p