fix @mc-hamster build to work on linux/nrf52

src/mesh/http/ContentHelper.cpp

@@ -0,0 +1,14 @@
+#include "mesh/http/ContentHelper.h"
+//#include <Arduino.h>
+//#include "main.h"
+
+void replaceAll(std::string &str, const std::string &from, const std::string &to)
+{
+    if (from.empty())
+        return;
+    size_t start_pos = 0;
+    while ((start_pos = str.find(from, start_pos)) != std::string::npos) {
+        str.replace(start_pos, from.length(), to);
+        start_pos += to.length(); // In case 'to' contains 'from', like replacing 'x' with 'yx'
+    }
+}