[keyserver] Determine which ids to fetch based on specs

Summary:
Specify for which entry types we would like to narrow down the data we're synchronizing and determine a set of ids to fetch based on that.

https://linear.app/comm/issue/ENG-4631/migrate-checkstate-from-session-utils-to-a-spec

Depends on D8949

Test Plan: Modify keyserver db and check if the store get fixed.

Reviewers: kamil, bartek, inka

Reviewed By: bartek

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D8976