Fix the string counting a selected files/dirs
Fix the string counting a selected files/dirs

The old one contains untranslatable ' & ' if both files and dirs are
selected. The new code is especially designed to reuse strings from file
listing summary view (apps/files/js/filesummary.js), so no translation
is broken.

pollopolea/core,whitekiba/server,michaelletzgus/nextcloud-server,IljaN/core,whitekiba/server,endsguy/server,lrytz/core,jbicha/server,phil-davis/core,pmattern/server,pixelipo/server,pmattern/server,owncloud/core,owncloud/core,pixelipo/server,xx621998xx/server,xx621998xx/server,michaelletzgus/nextcloud-server,whitekiba/server,lrytz/core,owncloud/core,IljaN/core,jbicha/server,Ardinis/server,pixelipo/server,owncloud/core,IljaN/core,pollopolea/core,cernbox/core,andreas-p/nextcloud-server,lrytz/core,nextcloud/server,jbicha/server,andreas-p/nextcloud-server,andreas-p/nextcloud-server,whitekiba/server,michaelletzgus/nextcloud-server,pollopolea/core,xx621998xx/server,bluelml/core,Ardinis/server,bluelml/core,bluelml/core,jbicha/server,pixelipo/server,endsguy/server,cernbox/core,bluelml/core,endsguy/server,cernbox/core,pmattern/server,nextcloud/server,owncloud/core,lrytz/core,pixelipo/server,cernbox/core,pollopolea/core,nextcloud/server,cernbox/core,Ardinis/server,andreas-p/nextcloud-server,endsguy/server,bluelml/core,sharidas/core,sharidas/core,pmattern/server,sharidas/core,IljaN/core,IljaN/core,pollopolea/core,Ardinis/server,xx621998xx/server,andreas-p/nextcloud-server,michaelletzgus/nextcloud-server,whitekiba/server,xx621998xx/server,nextcloud/server,lrytz/core,sharidas/core,jbicha/server,endsguy/server,pmattern/server,sharidas/core,Ardinis/server