feat(skybock): Add Skyblock item class and getSkyblockItems

[BonnetAdam]

Changes

I've added SkyblockItem and getSkyblockItems

Checkboxes

• I've added new features. (methods or parameters)
• I've fixed bug. (optional you can mention a issue if there is one)
• I've corrected the spelling in README, documentation, etc.
• I've tested my code. (pnpm test)
• I've check for issues. (pnpm lint)
• I've fixed my formatting. (pnpm prettier)

[Kathund]

Hey I added tests for you but you need to fix either them or your code. This is the error that is being thrown

 FAIL  src/API/getSkyblockItems.test.ts > getSkyblockItems
AssertionError: expected undefined to be defined
 ❯ src/API/getSkyblockItems.test.ts:35:27
     33|     expect(item.id).toBeDefined();
     34|     expectTypeOf(item.id).toEqualTypeOf<string>();
     35|     expect(item.category).toBeDefined();
       |                           ^
     36|     expectTypeOf(item.category).toEqualTypeOf<string>();
     37|     expect(item.npcSellPrice).toBeDefined();
 ❯ src/API/getSkyblockItems.test.ts:21:8