- Reuse these methods on determineIcon()
- Generate permission string for the desktop client
- expose {http://owncloud.org/ns}permissions as additional WebDAV property containing the permission string

This patch was automatically generated as part of the following inspection:
https://scrutinizer-ci.com/g/owncloud/core/inspections/cdfecc4e-a37e-4233-8025-f0d7252a8720

Enabled analysis tools:
 - PHP Analyzer
 - JSHint
 - PHP Copy/Paste Detector
 - PHP PDepend

Add a FileInfo class which holds all info of a file and return that from getFileInfo, getDirectoryContent and search