Notify: add firmware update flag and implement for OreoLED

libraries/AP_Notify/AP_Notify.h

@@ -89,6 +89,7 @@ public:
         uint16_t autotune_next_axis     : 1;    // 1 when autotune has completed one axis and is moving onto the next
         uint16_t mission_complete       : 1;    // 1 when the mission has completed successfully
         uint16_t waypoint_complete      : 1;    // 1 as vehicle completes a waypoint
+        uint16_t firmware_update        : 1;    // 1 just before vehicle firmware is updated
     };
 
     // the notify flags are static to allow direct class access

libraries/AP_Notify/OreoLED_PX4.cpp

@@ -88,6 +88,12 @@ void OreoLED_PX4::update()
         return;
     }
 
+    // handle firmware update event
+    if (AP_Notify::events.firmware_update) {
+        set_macro(OREOLED_INSTANCE_ALL, OREOLED_PARAM_MACRO_COLOUR_CYCLE);
+        return;
+    }
+
     // return immediately if custom pattern has been sent
     if (OreoLED_PX4::_pattern_override != 0) {
         // reset stage so patterns will be resent once override clears