Rewrite all the code for ShulkerBoxPreview to support versions 1.20 to 1.20.6.
Most of the functionalities should remain the same.
Please make sure to reset the config.yml file in plugin/ShulkerPreviewer,
and assign permissions to players based on the permission nodes specified.

將 ShulkerBoxPreview 全部代碼重寫，支援 1.20 ~ 1.20.6 ，
大部分功能一致，請務必重新於 plugin/ShulkerPreviewer 中，
設定 config.yml 內容，並根據其權限節點，分配權限給玩家。