Follow up to 2699 - check download state on cell creation

* Ref https://github.com/nextcloud/talk-ios/pull/2699

Check if we can retrieve the download state on cell creation already, not only when the progress notification is posted.

Start by reviewing pull request 2699 and the cell-creation and progress-notification handling it changes. Check whether the download state can be retrieved when a cell is created, and consider the work done when the cell reflects that state without waiting for a progress notification.

Written by the indexing model from the issue text.