Feature: Allow to change the maximum stack size of custom vanilla item mappings

[BUGTeas]

Now Java editon have the max_stack_size component to allow user change the maximum stack size of vanilla items butween 1~99. But Bedrock only support it in addon-defined items, so it's imperfect use.

This pull allow to customize the maximum stack size during the Bedrock item registration. to improve the experience as much as possible.

Example usage of this pull

JSON mappings:

{
  "format_version": "1",
    "items": {
      "minecraft:snowball": [
      {
        "custom_model_data": 101,
        "name": "custom_snowball",
        "max_stack_size": 64
      }
    ]
}

Extension API:

CustomItemData data = CustomItemData.builder()
        .name("custom_snowball")
        .customItemOptions(itemOptions)
        .stackSize(64)
        .build();

[onebeastchris]

Hello! Thanks for the PR.
However, the V2 version of the custom items api that is currently in the works - see #5189 for reference - will already implement this feature, and when it releases, the current custom item api (v1) will be deprecated in favor of the new version . Thank you anyways!