Adding changes can be slow due to a slow query to get latest snapshots

[hahn-kev]

The particular query that's slow is here:

harmony/src/SIL.Harmony/DataModel.cs

Lines 211 to 225 in 803b3bd

	private async Task<SimpleSnapshot[]> GetEntitySnapshots(bool includeDeleted = false)
	{
	var queryable = _crdtRepository.CurrentSnapshots();
	if (!includeDeleted) queryable = queryable.Where(s => !s.EntityIsDeleted);
	var snapshots = await queryable.Select(s =>
	new SimpleSnapshot(s.Id,
	s.TypeName,
	s.EntityId,
	s.CommitId,
	s.IsRoot,
	s.Commit.HybridDateTime,
	s.Commit.Hash,
	s.EntityIsDeleted)).AsNoTracking().ToArrayAsync();
	return snapshots;
	}

to reproduce import a decent sized fw project into crdts, then try making some changes. That query above should be a big bottleneck in performance.

[hahn-kev]

fixed in #12