Additional Primary Index for <ActId,EventId> in AttributeTable

[datagramdb]

Fast accessing to each beginning of the trace. Idea by Sam.

[datagramdb]

Keeping this in the loop!
With the new version of the code, and specifically in line https://github.com/datagram-db/knobab/blob/de9d5f9cd8f5f5687b5d29d958c14fd5ed650d22/src/knobab/server/ndp/NDPAttributeTable.cpp#L120, we are attempting to achieve this via clustered indices.

This issue will be closed once the v2.0 pipeline is eventually debugged.