feat: add mqtt client version to repeater app and cli

src/helpers/mqtt/MQTTUplink.h

@@ -55,6 +55,7 @@ public:
   bool isTxEnabled() const { return _prefs.tx_enabled != 0; }
   bool setIata(const char* iata);
   const char* getIata() const { return _prefs.iata; }
+  const char* getClientVersion() const;
   void setNodeNameSource(const char* node_name) { _node_name = node_name; }
   bool setOwnerPublicKey(const char* owner_public_key);
   const char* getOwnerPublicKey() const { return _prefs.owner_public_key; }