Add support for Denizen items

[mergu]

Select the option(s) that best describes this PR:

• [ ] Major breaking change
• [ ] Minor change
• [ ] Bug fix
• [x] Feature implementation
• [ ] Documentation
• [ ] Cleaning
• [ ] Refactoring

Please describe the changes this PR makes and why it should be merged:

Denizen is a powerful scripting language primarily used for Citizens NPCs, but also has a large community of users who use it for general-purpose scripting. This PR adds support for Denizen scripted items.

Tested via:

# Denizen script
custom_item:
  type: item
  material: blaze_rod
  display name: <&gradient[from=#00ff00;to=#0000ff]>My custom item
  mechanisms:
    custom_model_data: 1
  lore:
    - Some lore, <util.time_now.format>

# Cosmetic linked to script
custom_item:
  slot: OFFHAND
  permission: "hmccosmetics.custom_item"
  item:
    material: denizen:custom_item

Check that:

• [x] Any new classes, public methods and/or properties are properly documented with JavaDocs
• [x] Syntax and style are consistent with existing code
• [x] Any replaced method isn't deleted, but rather labeled as deprecated

  Note In the case where the new method has the exact same signature as the method it's replacing, mention above that the old method was deleted.

[mergu]

This closes https://github.com/HibiscusMC/HMCCosmetics/issues/98

[Craftinators]

Looks good ❤️