chore(android): add a function to clear a shared pref value

android/app/src/main/java/com/vernu/sms/helpers/SharedPreferenceHelper.java

@@ -44,4 +44,11 @@ public class SharedPreferenceHelper {
         SharedPreferences settings = context.getSharedPreferences(PREF_FILE, 0);
         return settings.getBoolean(key, defValue);
     }
+
+    public static void clearSharedPreference(Context context, String key) {
+        SharedPreferences settings = context.getSharedPreferences(PREF_FILE, 0);
+        SharedPreferences.Editor editor = settings.edit();
+        editor.remove(key);
+        editor.apply();
+    }
 }