IoStore package id index ignores ReadOrder

[wondercrash]

When a patch pak overrides a package, looking that package up by path gives you the patched one, but
looking it up by package id can give you the old one.

pakchunk0:    A.uasset
pakchunk0_P:  A.uasset // higher ReadOrder

by path -> patched pak
by id   -> either one  (whichever pak was mounted last)

Path lookups sort by ReadOrder on every lookup, but the id index just overwrites as paks are mounted.

CUE4Parse/CUE4Parse/FileProvider/Vfs/FileProviderDictionary.cs

Lines 109 to 112 in 46729b7

	if (file is FIoStoreEntry { IsPackageData: true, IsOptionalPackage: false } ioEntry)
	{
	(packageIndex ??= GetPackageIndex())[ioEntry.ChunkId.AsPackageId()] = file;
	}

I encountered this issue through FModel on the game Neverness to Everness. I exported an AnimMontage which only existed in the patch pak. But because the montage's Skeleton is an import, it resolved by id to the pre-patch skeleton which has a different bone list, so the animation got mapped onto the wrong bones.

I have a patch that works for my use case, but I'm not too familiar with UE and how this would affect other games so I opened an issue first.
wondercrash@c81ed0a

This issue was written with AI assistance.