MBS-9449_Filereport_for_uploaded_files

[bblumenfelder]

• Implemented filereport-property in manager.php that stores stats about imported or skipped files.
• Template filereport.mustache shows bootstrap collapsible component with filelist

Possible improvements:

• manager.php in Line 278ss.

                    // Parse metadata.json and get 'filename'-value.
                    if ($file->get_filename() == 'metadata.json') {
                        $targetfilename = json_decode($file->get_content(), true)['filename'];
                    }

metadata.json is parsed twice with conflicts with DRY-principle