Send document updates by batch

[kerwanp]

Description

Today, document updates (update and delete) are sent to the Search engine one by one. And it is a behavior that can lead to a lot of issues when mass updating records.

Proposal

Documents should be sent by batch with the following behavior:

• When updating or deleting records, the "action" should be stored in a queue.
• If the queue reach a configurable amount of updates to be done, the queue is processed.
• If the queue does not receive new updates to be done after a configurable delay, the queue is processed.
• It should be possible to manually flush the queue. magnify.engine().flushQueue()