Add SignalModifiedKey hook in XGROUP CREATE with MKSTREAM option (#7562)

(cherry picked from commit f33acb3f029d7f5aa68e22e612036e04417e3e91)

src/t_stream.c

@@ -1841,6 +1841,7 @@ NULL
             o = createStreamObject();
             dbAdd(c->db,c->argv[2],o);
             s = o->ptr;
+            signalModifiedKey(c,c->db,c->argv[2]);
         }
 
         streamCG *cg = streamCreateCG(s,grpname,sdslen(grpname),&id);