…coded sql query

…stic

…nually and verify the performance as part of a test

…red with `ChangesToSnapshotsAreNotSaved`. Fixing that uncovered tests that depend on snapshots being tracked between test phases. Also fixed tests which were over-specifying the expected time when there was a mismatch in time offset that was acceptable.

…mplement the matching return type without restricting the collection type. Split `GetChanges` helper to `GetMissingCommits` which returns an IAsyncEnumerable, this allows the server to use less memory when responding to requests with a large number of commits

…pplication restart

… creating a new data model instance.

…query

…its, lookup just the ids for entities changed