TASK: Add indices to improve parent/child query performance

[kitsunet]

We did not have any index on the parentnodeanchor, additionally the anchors should be first, as they are most likely the most discriminating part of the query, also position was added, to potentially improve sort queries.

Upgrade instructions

run ./flow cr:setup

[kitsunet]

Haha, just if anyone is wondering, We did not have any index on the parentnodeanchor is not true if you inspect the code, it's just that the index is only on parentnodeanchor which in the complexity of the query(s) we perform doesn't help much. I guess in a follow up we might remove that one, I first want to check other typical queries though, not that we need it somewhere else.