Abilities or functions to expand inventory limit

[BenCheung0422]

Is your feature request related to a problem? Please describe.
As we have an inventory limitation system, we should have an enhancement to expand the inventory limit in the late game as a reward or equipment. In #201, "Enchantment of holding" is mentioned, intending to directly increase the inventory slot count limit permanently. However, from Minecraft, functionalities to utilize limits (bundle) and extra carrier (shulker box) are interesting and extensive to the system.

Describe the solution you'd like
We could have bags, backpacks, arrow bundles, portable chests, etc. "Enchantment of holding" might be either too powerful or useless, so equipment as the abilities would be a better choice. In these examples:

• Bags: an item to give some extra slots when interacted; it could have a similar mechanics of bundle in Minecraft or backpack below.
• Backpacks: an equipment that can be armored without occupying an inventory slot; it gives some extra slots with associated keys (implemented with ContainerDisplay).
• Arrow bundles: the maximum count of arrows would be reduced in a slot to make this more useful; an arrow bundle requires some materials to craft an empty arrow bundle; it could either be armored or stayed in the player inventory; it allows players to put arrows into an arrow bundle until it reaches the maximum size; it would have a greater maximum size than a bare arrow slot.
• Portable chests: it would have similar mechanics like a shulker box; it can be picked up to the inventory when it contains items, unlike normal chests; it can only be opened when placed; it would require a higher cost to balance the game.

In ideal, there should be different stack size limits to different items to ideally balance the game.