OptionalIndexA secondary index within the category that this key belongs to. LocalCacheManager
passes the entity name for RunView cache entries, so a shared provider can answer
ILocalStorageProvider.GetIndexGroupKeys without listing the whole category.
OptionalTTLSeconds until the entry expires, overriding the provider's default. 0 stores the entry
without expiry. Omit to use the provider's default.
Per-write options for ILocalStorageProvider.SetItem.