[debug] Add min_free heap sensor for ESP32 and LibreTiny, add fragmentation for ESP32 (#13231)

esphome/components/debug/debug_libretiny.cpp

@@ -51,6 +51,9 @@ void DebugComponent::update_platform_() {
   if (this->block_sensor_ != nullptr) {
     this->block_sensor_->publish_state(lt_heap_get_max_alloc());
   }
+  if (this->min_free_sensor_ != nullptr) {
+    this->min_free_sensor_->publish_state(lt_heap_get_min_free());
+  }
 #endif
 }