[Shared Tasks] Implement Activity Locking (#2339)

* Add shared task element locking

This adds the `lock_activity_id` field to the tasks table which will
automatically lock a shared task when that element becomes active.

A method was added to world analogous to zone's UnlockActivities to
determine when an activity is active with respect to task steps.

Also adds quest apis to manually lock or unlock a client's shared task

* Add comment

world/zoneserver.cpp

@@ -1394,6 +1394,7 @@ void ZoneServer::HandleMessage(uint16 opcode, const EQ::Net::Packet &p) {
 		case ServerOP_SharedTaskCreateDynamicZone:
 		case ServerOP_SharedTaskPurgeAllCommand:
 		case ServerOP_SharedTaskPlayerList:
+		case ServerOP_SharedTaskLock:
 		case ServerOP_SharedTaskKickPlayers: {
 			SharedTaskWorldMessaging::HandleZoneMessage(pack);
 			break;