With the new version of Visual Studio bringing C# 12, we can revise our logic for better readability as well as use new methods/APIs introduced in the .NET 8.0 BCL.
- Add HeldItems_XY
- Fix that HeldItem_AO pointed to what should have been HeldItems_XY
- Fix HeldItem_AO being inconsistent with the rest of the HeldItems
- Correct HeldItems_AO only having XY held items and not ones added in ORAS
* Extract/encapsulate inventory legal arrays to interface+class
Hiding them behind methods allows these to be left as ReadOnlySpan<ushort> and thus never allocate on the heap.
Also refactors out some logic for checking if an item is legal.
End result feels more maintainable and is less bloaty (no more passing in a nullable func)
Batch editing
* Add HasType filter
```
=HasType=11
.HeldItem=Meadow Plate
```
slaps a meadow plate on any pkm with grass type
Use `=PersonalType1=11` for only primary grass types; only-secondary-type grass will not match it.
