Add NVS storage handler and integrate with main application logic

main/io/nvs_handler.h

@@ -0,0 +1,21 @@
+#pragma once
+#include "io/io.h"
+#include "freertos/FreeRTOS.h"
+#include "nvs.h"
+
+class NVSStorageHandler : public KVStorageHandler {
+public:
+  NVSStorageHandler() = default;
+  ~NVSStorageHandler() override;
+
+  void init(const EventGroupHandle_t& system_event_group) override;
+
+  void put(const char*& key, const char*& value) override;
+
+  char* get(const char*& key) const override;
+
+  void remove(const char*& key) override;
+
+private:
+  nvs_handle_t nvsHandle = 0;
+};