Implement parameters subsystem

* Unified parameters storage.
* Store parameters in flash on the hardware.
* Store parameters in text file in simulation.
* Work with parameters in command line.
* Support parameters in MAVLink for working with parameters in QGC.

gazebo/Preferences.h

@@ -0,0 +1,63 @@
+// Copyright (c) 2024 Oleg Kalachev <okalachev@gmail.com>
+// Repository: https://github.com/okalachev/flix
+
+// Partial implementation of the ESP32 Preferences library for the simulation
+
+#include <map>
+#include <fstream>
+#include "util.h"
+
+class Preferences {
+private:
+	std::map<std::string, float> storage;
+	std::string storagePath;
+
+	void readFromFile() {
+		std::ifstream file(storagePath);
+		std::string key;
+		float value;
+		while (file >> key >> value) {
+			storage[key] = value;
+		}
+	}
+
+	void writeToFile() {
+		std::ofstream file(storagePath);
+		for (auto &pair : storage) {
+			file << pair.first << " " << pair.second << std::endl;
+		}
+	}
+
+public:
+	bool begin(const char *name, bool readOnly = false, const char *partition_label = NULL) {
+		storagePath = getPluginPath().parent_path() / (std::string(name) + ".txt");
+		gzmsg << "Preferences initialized: " << storagePath << std::endl;
+		readFromFile();
+		return true;
+	}
+
+	void end();
+
+	bool isKey(const char *key) {
+		return storage.find(key) != storage.end();
+	}
+
+	size_t putFloat(const char *key, float value) {
+		storage[key] = value;
+		writeToFile();
+		return sizeof(value);
+	}
+
+	float getFloat(const char *key, float defaultValue = NAN) {
+		if (!isKey(key)) {
+			return defaultValue;
+		}
+		return storage[key];
+	}
+
+	bool clear() {
+		storage.clear();
+		writeToFile();
+		return true;
+	}
+};