feat: Adds utility to check internet connection

Provides a helper function `checkInternetConnexion` using the `connectivity_plus` package. It returns true for network types typically used for internet access (mobile, wifi, ethernet, vpn) and false otherwise.

lib/utils/utils.dart

@@ -1,3 +1,4 @@
+import 'package:connectivity_plus/connectivity_plus.dart';
 import 'package:flutter/material.dart';
 
 extension StatefulWidgetExtensions on State<StatefulWidget> {
@@ -9,3 +10,40 @@ extension StatefulWidgetExtensions on State<StatefulWidget> {
     }
   }
 }
+
+Future<bool> checkInternetConnexion() async {
+  final List<ConnectivityResult> connectivityResult = await (Connectivity()
+      .checkConnectivity());
+
+  // This condition is for demo purposes only to explain every connection type.
+  // Use conditions which work for your requirements.
+  if (connectivityResult.contains(ConnectivityResult.mobile)) {
+    // Mobile network available.
+    return true;
+  } else if (connectivityResult.contains(ConnectivityResult.wifi)) {
+    // Wi-fi is available.
+    // Note for Android:
+    // When both mobile and Wi-Fi are turned on system will return Wi-Fi only as active network type
+    return true;
+  } else if (connectivityResult.contains(ConnectivityResult.ethernet)) {
+    // Ethernet connection available.
+    return true;
+  } else if (connectivityResult.contains(ConnectivityResult.vpn)) {
+    // Vpn connection active.
+    // Note for iOS and macOS:
+    // There is no separate network interface type for [vpn].
+    // It returns [other] on any device (also simulator)
+    return true;
+  } else if (connectivityResult.contains(ConnectivityResult.bluetooth)) {
+    // Bluetooth connection available.
+    return false;
+  } else if (connectivityResult.contains(ConnectivityResult.other)) {
+    // Connected to a network which is not in the above mentioned networks.
+    return false;
+  } else if (connectivityResult.contains(ConnectivityResult.none)) {
+    // No available network types
+    return false;
+  } else {
+    return false;
+  }
+}