Move inject-a-key-into-a-value-using-a-key-path to event-loop steps

[gterzian]

inject-a-key-into-a-value-using-a-key-path is called from store a record into an object store , itself scheduled as part of asynchronously execute a request, which runs the operation in-parallel. But, injecting a key into a value manipulates script objects, and so it cannot run in-parallel, instead the key should be injected when the request has been processed, by way of a queued task back on the event-loop.

It's also not clear if the key injection should be reverted if the transaction containing the request is aborted.