Add explicit check for groups excluded from sharing
Add explicit check for groups excluded from sharing

Since isSharable() doesn't do the check for groups excluded from
sharing, adding an explicit check in the sharing code.

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