Support item matcher in itemmods

[Pablete1234]

Allows for item-mods to have a matcher subelement for match which is an item matcher definition, such as those found in holding/carrying filters or replace-item/enchant-item actions.

eg:

<item-mods>
    <rule>
        <match ignore-metadata="true">
            <matcher material="bow" amount="1"/>
        </match>
        <modify show-enchantments="false" unbreakable="true">
            <enchantment level="2">infinity</enchantment>
        </modify>
    </rule>
</item-mods>

Do note: item-mods still apply JUST ONCE whenever the item is first observed (eg: when a chest is opened, or when the kit is created), so things like trying to modify the item when it gets to a certain durability, or if it gets enchanted with something after the fact is not and will not be supported.

This is more of a prototype because it was requested by a mapdev, but i'm not convinced this actually solves their intended use-case which was modifying punch bows in chests, as itemmods can only add not remove stuff. Also not convinced on the xml name for it, but we can't really use material or item as either of those are already interpreted as being materials for the material matcher.

[eliminate123]

Good work pablete. this is a certified hood classic 👍