Add envoy support to solar logger

include/solar/logger/zeverdata.hpp

@@ -2,6 +2,7 @@
 #include <cstdio>
 #include <ctime>
 #include <curl/curl.h> // tested with libcurl4-openSSH
+#include <optional>
 #include <sstream>
 #include <string>
 
@@ -25,9 +26,7 @@ struct ZeverData
     std::string OKmsg, ERRORmsg;
 
     // Parses the data string coming from the zeverlution home.cgi webpage
-    bool ParseString(const std::string & str);
-
-    bool FetchDataFromURL(const std::string & url, const unsigned int timeout);
+    static std::optional<ZeverData> ParseString(const std::string & str);
 
     ZeverData();
 };