First process group shares and then user shares (#26526)
First process group shares and then user shares (#26526)

This prevents a validation failure where the code checks whether a file
is already shared with another user, but the check disables itself when
the owner is the same. Processing the groups first prevents the check
to kick in too early when the group share still has the old owner while
we try transferring the user share.
IljaN/core,owncloud/core,IljaN/core,IljaN/core,IljaN/core,IljaN/core,pollopolea/core,phil-davis/core,owncloud/core,owncloud/core,sharidas/core,pollopolea/core,sharidas/core,pollopolea/core,sharidas/core,owncloud/core,sharidas/core,owncloud/core,sharidas/core,pollopolea/core,pollopolea/core