FDataDrivenPlatformInfoRegistry::GetValidPlatformDirectoryNames

Gets a set of platform names based on GetAllPlatformInfos, their AdditionalRestrictedFolders, and possibly filtered based on what editor has support compiled for This is not necessarily the same as IniParents, although there is overlap - IniParents come from chaining DDPIs, so those will be in GetAllPlatformInfos already to be checked