Allow more operations that just adding pools

[OffsetMonkey538]

(This isn't going to be done soon, just thought I should make an issue for it so I have somewhere to put my ideas when I get some)

First need to come up with a nice format for matching what to modify.
Should match loot table name, specific entries based on type, value and functions (at least the function name, if not specific data).

Everything should support regex (could do otherPack:.* for all loot from another pack, could do .*:entities/.* to match any entity table from any pack) and the conditions should be in an AND relationship.

Kind of like mixins but for loot tables haha

Should have different operations to do with the matched loot tables or entries: add, remove,

[OffsetMonkey538]

and between conditions in an array, it should use OR between them