Add QueueStatus sending to the firmware (#1820)

* Yank mqtt service envelope queue

* trybuildfix mqtt system

* removed too much

* no excessive heap debugging on release builds

* send QueueStatus messages

The QueueStatus message is sent as a response to the attempt to queue
an outgoing MeshPacket and contains statuses of the last queue
attempt, TX Queue space and capacity and MeshPacket.id that was
queued.

When TX Queue changes status from completely full to at least
a single slot free a QueueStatus message is also sent to notify
that user can queue more messages.

Signed-off-by: Pavel Boldin <pavel.b@techspark.engineering>

* WIP: update protobufs

Signed-off-by: Pavel Boldin <pavel.b@techspark.engineering>

* update protobufs

* regen protos

Signed-off-by: Pavel Boldin <pavel.b@techspark.engineering>
Co-authored-by: Ben Meadors <benmmeadors@gmail.com>
Co-authored-by: Thomas Göttgens <tgoettgens@gmail.com>
Co-authored-by: Sacha Weatherstone <sachaw100@hotmail.com>

src/mesh/MeshPacketQueue.h

@@ -26,6 +26,12 @@ class MeshPacketQueue
     /** return true if the queue is empty */
     bool empty();
 
+    /** return amount of free packets in Queue */
+    size_t getFree() { return maxLen - queue.size(); }
+
+    /** return total size of the Queue */
+    size_t getMaxLen() { return maxLen; }
+
     MeshPacket *dequeue();
 
     MeshPacket *getFront();