feat: support batching operations together

[mvayngrib]

the problem

set/delete are currently per-key, and result in the entire file being written

solution

a batch api lets the caller maintain a kind of queue, and flush all writes at the end

const promise = store.batch()
  // add as many operations as you want
  .add({ type: 'set', key: 'abc', value: '123' })
  .add({ type: 'delete', key: 'efg' })
  // flush
  .exec()

the main problem will probably be solved by https://github.com/ExodusMovement/exodus-desktop/pull/8034 and https://github.com/ExodusMovement/exodus-desktop/pull/8035 but it would still be nice to be able to batch ops together and save time on writes

the below is what i get on restore on master with batching added on top of master (ignore the times, the blue numbers are the batch sizes):

when running on top of the PRs linked above, it's way better, but might still be worth it in case we have bursts:

[kklash]

Unclear on context of the problem that this PR solves. Please elaborate PR description with some background.

[mvayngrib]

@kklash haha ur absolutely right. Does the updated description clarify things?

[kklash]

Yes, thanks @mvayngrib

[mvayngrib]

closing in favor of one or more of #12 #13 #14