added sqlite connection class (progress)

include/matador/utils/os.hpp

@@ -0,0 +1,14 @@
+#ifndef QUERY_OS_HPP
+#define QUERY_OS_HPP
+
+#include <string>
+
+namespace matador::utils::os {
+
+std::string getenv(const char* name);
+
+[[maybe_unused]] std::string getenv(const std::string &name);
+
+}
+
+#endif //QUERY_OS_HPP