fdo#51741 Mark document as modified on bookmark rename / delete

Change-Id: I378037ea546d0f2dc4ab9e0b0e6f9bf65c8db5b4
Deletion: overrided DdeBookmark::DeregisterFromDoc in Bookmark
Renaming: in MarkManager::renameMark
Reviewed-on: https://gerrit.libreoffice.org/12436
Reviewed-by: Michael Stahl <mstahl@redhat.com>
Tested-by: Michael Stahl <mstahl@redhat.com>