New pagination / button + PacketManager API access

[1robie]

This pull request introduces a robust pagination system for inventory GUIs and refines several API interfaces to improve extensibility and usability. The main focus is on adding a PaginationManager API and related button abstractions to support paginated inventory content, along with some configuration and API enhancements.

Pagination system and inventory API enhancements:

• Added a new PaginationManager API (PaginationManager.java) for managing paginated inventory states per player and context, including methods for page navigation, state management, and max page tracking.
• Introduced abstract button classes for paginated GUIs:
  • GenericPaginateButton provides page navigation and state helpers for paginated buttons.
  • GenericPaginationButton<T> extends GenericPaginateButton to render paginated elements in inventory slots, handling element slicing and placeholder registration for current/max page.
• Exposed the PaginationManager via the InventoryManager interface, allowing plugins to access and use the pagination system for inventory GUIs. [1] [2]

API and configuration improvements:

• Added a PacketManager API (PacketManager.java) for inventory title editing and lifecycle hooks, and exposed it as an optional method in the MenuPlugin interface. [1] [2] [3]
• Added a new configuration option skipCloseActionsOnInventorySwitch to Configuration.java, allowing certain inventory switches to skip close actions, with corresponding load/save logic and config path. [1] [2] [3] [4]

Item stack component refinement:

• Refactored CustomModelDataComponent to use non-optional lists for its fields, simplifying its API and usage, and updated the application logic accordingly. [1] [2]