Add config parameter removal

Config parameters can now be removed. Grouped the related functions closer
to each other in config.cc.

server/core/internal/config.h

@@ -111,6 +111,14 @@ bool config_append_param(CONFIG_CONTEXT* obj, const char* key, const char* value
  */
 bool config_replace_param(CONFIG_CONTEXT* obj, const char* key, const char* value);
 
+/**
+ * @brief Remove a parameter
+ *
+ * @param obj Configuration context
+ * @param key Name of the parameter to remove
+ */
+void config_remove_param(CONFIG_CONTEXT* obj, const char* name);
+
 /**
  * @brief Construct an SSL structure
  *