feature: Implemented Helper::shuffleString() in Helper module

We already had a function `Helper::shuffle()` that can be use for shuffling a
vector of objects but it wasn't possible to use it for a std::string and
shuffle it chars

`Helper::shuffleString()` can be use to generate random permutations of a given
std::string

include/faker-cxx/Helper.h

@@ -143,6 +143,19 @@ class Helper
         return data;
     }
 
+    /*
+     * @brief Returns shuffled std::string
+     *
+     * @param data String to be shuffled
+     *
+     * @return std::string with shuffled chars
+     *
+     * @code
+     * Helper::shuffleString("hello") // "eollh"
+     * @endcode
+     */
+    static std::string shuffleString(std::string data);
+
     // TODO: remove methods below from helper API, move to src/common
 
     /**

src/modules/helper/Helper.cpp

@@ -1,5 +1,6 @@
 #include "faker-cxx/Helper.h"
 
+#include <algorithm>
 #include <chrono>
 #include <random>
 #include <regex>
@@ -15,6 +16,12 @@ std::random_device Helper::randomDevice;
 
 std::mt19937 Helper::pseudoRandomGenerator(Helper::randomDevice());
 
+std::string Helper::shuffleString(std::string data)
+{
+    std::shuffle(data.begin(), data.end(), pseudoRandomGenerator);
+    return data;
+}
+
 std::string Helper::replaceSymbolWithNumber(std::string str, const char& symbol)
 {
     for (char& ch : str)