This PR updates for the new query-index API. The original formulation of query-index was not actually very usable as it was intended.
The new query-index API returns events sorted by time for a particular content-type, and then some associated feed integrity proof stuff that can be ignored for now.
As part of this deletes need to include some extra indexing information about the original event.
Lastly where query-index was originally being used to load the latest for some set of content-types (such as username, description), there is now 'queryLatest' which handles that case.
Note that the server component of this is not currently deployed but can be whenever PlatformPlayer is ready / you want it to be.