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

(cherry picked from commit 0a2b019b79831e6c593c2de943af61ceef4327e1)

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);