MSTP update - 3: added component xSTP activation handler

Added #bridge #component level #spanning-tree #activation #handler in MSTP module. On activating the spanning tree in a component it #enable s #xSTP #protocol s on the component. When disabled the xSTP protocols wont be running over the component ports.

#802-1S MSTP update 3 ...
[commit 7760a5e097bd03bb5a7f74979c90ab6615d6594b]