feat: Integrate VND7050AJ driver and enhance gateway settings

This commit introduces the VND7050AJ driver as a new submodule and integrates it into the project.

Key changes include:
- Added  as a git submodule.
- Enhanced the gateway application () with LittleFS and the settings subsystem.
  - Implemented new shell commands (, , ) for managing custom settings.
  - Added functionality to compact the settings file.
- Updated  to include new library dependencies and log  return code.
- Adjusted include paths for  in relevant files.
Signed-off-by: Eduard Iten <eduard@iten.pro>

software/apps/slave_node/boards/native_sim.overlay

@@ -0,0 +1,47 @@
+/ {
+	aliases {
+		vnd7050aj = &vnd7050aj;
+	};
+
+	vnd7050aj: vnd7050aj {
+		compatible = "st,vnd7050aj";
+		status = "okay";
+
+		input0-gpios = <&gpio0 1 GPIO_ACTIVE_HIGH>;
+		input1-gpios = <&gpio0 2 GPIO_ACTIVE_HIGH>;
+		select0-gpios = <&gpio0 3 GPIO_ACTIVE_HIGH>;
+		select1-gpios = <&gpio0 4 GPIO_ACTIVE_HIGH>;
+		sense-enable-gpios = <&gpio0 5 GPIO_ACTIVE_HIGH>;
+		fault-reset-gpios = <&gpio0 6 GPIO_ACTIVE_LOW>;
+		io-channels = <&adc0 0>;
+		r-sense-ohms = <1500>;
+		k-vcc = <4000>;
+	};
+
+	modbus_uart: uart_2 {
+		compatible = "zephyr,native-pty-uart";
+		status = "okay";
+		current-speed = <19200>;
+
+		modbus0: modbus0 {
+			compatible = "zephyr,modbus-serial";
+			status = "okay";
+		};
+	};
+
+};
+
+&adc0 {
+	#address-cells = <1>;
+	#size-cells = <0>;
+	ref-internal-mv = <3300>;
+	ref-external1-mv = <5000>;
+
+	channel@0 {
+		reg = <0>;
+		zephyr,gain = "ADC_GAIN_1";
+		zephyr,reference = "ADC_REF_INTERNAL";
+		zephyr,acquisition-time = <ADC_ACQ_TIME_DEFAULT>;
+		zephyr,resolution = <12>;
+	};
+};