Gift1: use IVs if required
Gift2: Enforce 0 TimeOfDay
Egg9: Require Egg Location to match encounter
PGT: keep requested gender in the event of antishiny
PGT: never yield Korean Ranger Manaphy for Format4
Simplify ushort range checks
Rename `EReader` bool to `IsEReader`
Extract Gender/Nature fetch for unfixed encounters
Remove Unown PIDIV branch when template has no Unown
Remove unnecessary loop for Pokewalker PID creation
https://projectpokemon.org/home/forums/topic/63429-bdsp-slate/
The "Give All" cheat will skip adding unobtainable items.
Since the BDSP-exclusive Treasure (slate/shard) are unable to held, they were also skipped. Revise the logic to allow them to be added via "Give All", but still disallowed as held items (separate arrays needed).
Also condense the logic for BCAT-Dmax crystal IDs since they're all sequential. Just iterate a range instead of a span.
* Uses LearnSource more throughout the codebase when appropriate, rather than loosely coupled pivot methods.
* Hides Learnset/EggMove data inside the LearnSource classes.
* Extracts functionality from the large Legal class & partial Table*.cs files into better performing helper classes.
* Cleans up some code from prior LearnSource commits.
* 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.
