Improve MQTT (#2091)

* moved functions

* use hostname as default MQTT maintopic if parameter is not set

* use hostname as default MQTT client ID

* Only send Homassistant Discovery and Static Topics on the first connect. Retry in next round if any topic failed

* .

* add missing return code usage

* send maintopic/connection on every round like the system topics

---------

Co-authored-by: CaCO3 <caco@ruinelli.ch>

code/components/jomjol_helper/Helper.cpp

@@ -963,3 +963,34 @@ std::string UrlDecode(const std::string& value)
 
     return result;
 }
+
+
+bool replaceString(std::string& s, std::string const& toReplace, std::string const& replaceWith) {
+    return replaceString(s, toReplace, replaceWith, true);
+}
+
+
+bool replaceString(std::string& s, std::string const& toReplace, std::string const& replaceWith, bool logIt) {
+    std::size_t pos = s.find(toReplace);
+
+    if (pos == std::string::npos) { // Not found
+        return false;
+    }
+
+    std::string old = s;
+    s.replace(pos, toReplace.length(), replaceWith);
+    if (logIt) {
+        LogFile.WriteToFile(ESP_LOG_ERROR, TAG, "Migrated Configfile line '" + old + "' to '" + s + "'");
+    }
+    return true;
+}
+
+
+bool isInString(std::string& s, std::string const& toFind) {
+    std::size_t pos = s.find(toFind);
+
+    if (pos == std::string::npos) { // Not found
+        return false;
+    }
+    return true;
+}