Storing typed elements in UObjects can easily lead to reference leaks if the elements aren't cleared prior to the UObject being left pending GC. This actually made UTypedElementList tricky to use, as you had to remember to manually empty it when you'd finished with it to avoid reference leaks, and we've had several cases now where that was done incorrectly.
To address this issue, we've moved element lists back to being a normal C++ class, FTypedElementList. However, unlike the original version of FTypedElementList (which was itself a UStruct), this version is always heap-allocated and referenced via a TSharedPtr/TSharedRef.
This gives us a nice middle-ground of a well defined lifetime (ie, no lingering references prior to GC) while still being efficient to pass around, including for scripting APIs via FTypedElementListProxy (which just wraps the TSharedPtr in a UStruct).
The downside of this approach is that we need to wrap the FTypedElementList functions that we want to expose to the scripting API (see UTypedElementListLibrary), however that is a far more reasonable burden than requring every user of the typed element framework to know and understand that UTypedElementList had to be manually cleared to avoid potentially hard to find reference leaks (especially if via leaked via scripting APIs).
The core of this change is to TypedElementList.h/.cpp, with TypedElementListFwd.h existing to forward declare the pointer types, and TypedElementListProxy.h and TypedElementListLibrary.h existing to declare the proxy type and wrapped functions used for scripting APIs. TypedElementSelectionInterface.h (and its implementations) provide an example of using FTypedElementListProxy within a scripting API, and the rest of the change is mostly just fallout to transform const UTypedElementList* to FTypedElementListConstRef and UTypedElementList* to FTypedElementListRef.
#rb Brooke.Hubert
#preflight 60d2720c634cd100016c804b
[CL 16776547 by Jamie Dale in ue5-main branch]
For now, removing these as their semantics are due to change
Also converting Update and Become Relevant functions to use more-devived-typed update context (less casting required)
#rb Jurre.deBaare
[CL 16771205 by Thomas Sarkanen in ue5-main branch]
This is an extension of the fix for UE-117449, which focused on the case where the map being loadead was the only available newly created world. This handles the case where there may be multiple newly created worlds available when performing a map load, as this case would still present an error dialog that these worlds could not be unloaded.
#rb JeanMichel.Dignard
#preflight 60d388a0a8190400019186e8
[CL 16771187 by Jamie Dale in ue5-main branch]
Updating FVirtualizedUntypedBulkData and textures to use the BulkDataRegistry.
BulkDataRegistry: Add get/put accessors for the cached BulkDataList of packages.
EditorDomain: Move ClassDigests into a global variable that can be shared with BulkDataRegistry.
EditorDomain: Improve performance of GetFileSize by fetching metadata only.
Tickable Cook Objects, for systems used by the cooker that need to be ticked.
Implementation of the the BulkDataRegistry that uses the DDC cache for persistent storage of the BulkDataList.
#rb Devin.Doucette, Paul.Chipchase, Zousar.Shaker
[CL 16768772 by Matt Peters in ue5-main branch]
Static mesh instances are only hooked up editor side via hit proxies, and won't register in a sweep since it only deals with limited types.
#preflight 60ccd086be81e80001e90434
#Jira UETOOL-3724
#rb jamie.dale
#fyi basil.pesin
[CL 16763208 by brooke hubert in ue5-main branch]
