Create an index `last_modified_by'

[sneridagh]

We identified that it will be useful to have a last_modified_by index so we can query for content that has been recently modified by me through the site.

This has an application in the new link widget for Volto, so we can show the latest content that the current user has modified recently, so he can choose them right away.

/cc @davisagli @ericof @tisto

[davisagli]

We can consider this but I'm not sure it is the best way to implement what you want for the link widget.

If I create an item, then someone else edits it, it would not be included in the results even if I created it very recently.

Also, in a site with many editors working, it seems just as likely that I am trying to link to an item that I viewed recently but did not edit.

My suggestion would be to keep a list of recently viewed or edited items in localstorage, and use that for the link widget.

This would have the tradeoff that if the user edits the site using multiple devices, the list would not be kept in sync between them. I'm not sure if that is important.