Adds serial commands to get stats

- Added formatStatsReply, formatRadioStatsReply, and formatPacketStatsReply methods in MyMesh for both simple_repeater, simple_room_server, and simple_sensor.
- Updated CommonCLI to handle new stats commands.

examples/simple_repeater/MyMesh.cpp

@@ -787,6 +787,19 @@ void MyMesh::removeNeighbor(const uint8_t *pubkey, int key_len) {
 #endif
 }
 
+void MyMesh::formatStatsReply(char *reply) {
+  StatsFormatHelper::formatCoreStats(reply, board, *_ms, _err_flags, _mgr);
+}
+
+void MyMesh::formatRadioStatsReply(char *reply) {
+  StatsFormatHelper::formatRadioStats(reply, _radio, radio_driver, getTotalAirTime(), getReceiveAirTime());
+}
+
+void MyMesh::formatPacketStatsReply(char *reply) {
+  StatsFormatHelper::formatPacketStats(reply, radio_driver, getNumSentFlood(), getNumSentDirect(), 
+                                       getNumRecvFlood(), getNumRecvDirect());
+}
+
 void MyMesh::saveIdentity(const mesh::LocalIdentity &new_id) {
   self_id = new_id;
 #if defined(NRF52_PLATFORM) || defined(STM32_PLATFORM)