[batch] Add updates to batches

[daniel-goldstein]

An attempt to break open batches into a bunch of smaller PRs

[daniel-goldstein]

Can I also see the changes that follow after this set of PRs with the interaction between the client and how you account for update ids that aren't hardcoded to be 1?

Yes I'll put up a PR and tag you in it.

[jigold]

I just noticed that we didn't add a foreign key constraint on the jobs table for the batch update. I think unfortunately we should add it... thoughts?

[daniel-goldstein]

Ah yes, that was my mistake forgetting to add it in. I think these should all have FK constraints

[daniel-goldstein]

Got broken up and sent to relevant PRs