Fixed sharing status update for new/uploaded files

Creating new files, folders or uploading files now have their sharing
icon updated accordingly.

For this, the global share status list that is cached in
OC.Share.statuses is reused for new files.

Performance should improve as the sharing list is now only loaded once
per navigation session.

In OC.Share, split loadIcons into loadIcons + updateIcons.

Fixes #4977