Refactor NVS and WiFi handlers for improved memory management and logging

- Updated KVStorageHandler interface to use std::string instead of char* for key-value operations.
- Enhanced NVSStorageHandler to utilize ESP_LOG for error and info messages instead of printf.
- Refactored WifiHandler to manage WiFi credentials using JSON format for better structure and storage.
- Replaced raw pointers with std::unique_ptr in WifiHandler and NetworkHandler for automatic memory management.
- Removed unused TouchHandler and EInkTouchHandler classes to clean up the codebase.
- Adjusted CMakeLists.txt to remove unnecessary include directories.
- Updated lv_conf.h to enable FreeRTOS and gesture recognition features.

main/io/nvs_handler.h

@@ -53,14 +53,14 @@ public:
 
   void init(const EventGroupHandle_t& system_event_group) override;
 
-  void put(const char* const& key, const char* const& value) override;
+  void put(const std::string& key, const std::string& value) override;
 
-  std::unique_ptr<char[]> get(const char* const& key) const override;
+  std::string get(const std::string& key) const override;
   esp_err_t process_all(KeyValueProcessor processor, void* arg) const override;
-  esp_err_t process_filtered(const char* const& key_prefix, KeyValueProcessor processor, void* arg) const override;
+  esp_err_t process_filtered(const std::string& key_prefix, KeyValueProcessor processor, void* arg) const override;
   esp_err_t process_filtered(FilterFunc filter_func, KeyValueProcessor processor, void* arg) const override;
 
-  void remove(const char* const& key) override;
+  void remove(const std::string& key) override;
 
 private:
   NVSIteratorGuard create_iterator() const;