This combination of kvvfs callbacks seems to work okay for both persistent and transi...

This combination of kvvfs callbacks seems to work okay for both persistent and transient storage, but it's unclear why/how, as xAccess() does not appear to be doing anything useful (and misbehaves when told to report that the storage object in question exists). These tests fail in 64-bit builds for as-yet-unknown reasons (other tests continue to pass in 64-bit).

FossilOrigin-Name: 69e591d0054218ead789cee199e5258f1c378a89e4b7b0e38fe74e834e23156b