Add SetOption147

Add SetOption147  (MQTT) Enable publish SSerialReceived MQTT messages. If disabled, use event rules instead.
If it is disabled, tasmota will not publish an MQTT message every time a SSerialReceived event fires. Use rules to control how and when publish these messages.

tasmota/tasmota_support/settings.ino

@@ -838,6 +838,7 @@ void SettingsDefaultSet2(void) {
   SOBitfield3  flag3 = { 0 };
   SOBitfield4  flag4 = { 0 };
   SOBitfield5  flag5 = { 0 };
+  SOBitfield5  flag6 = { 0 };
   SysMBitfield1  flag2 = { 0 };
   SysMBitfield2  mbflag2 = { 0 };