'Boolean' is inconsistently shortened in serialization-related field names

[haykam821]

'Boolean' is shortened as 'bool' inconsistently within field names relating to serialization:

• PacketCodecs.BOOL field
• TrackedDataHandlerRegistry.BOOLEAN field

This inconsistency is most obvious when looking at the way the latter field is initialized:

public static final TrackedDataHandler<Boolean> BOOLEAN = TrackedDataHandler.create(PacketCodecs.BOOL);