insights: add a moving daily snapshot for insights over all repos

Created by: coury-clark

Closes #24186 (closed)

Adds functionality to one of the code insights background processes to record a daily snapshot. This will allow us to keep the overall cardinality low with longer intervals, but still provide some amount of near real time visibility into the insight.

The daily snapshot will only be persisted for each series for one data point. Any previous snapshots for each series will be deleted in the same transaction as the new snapshot.

Introduces new PersistMode to the insight series store that will toggle a recording or snapshot.