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.

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

Fixes #4977

Backport of 70c9652cdf6e00f1c62fb9a61d9dd4fb3e2c93c3