feat(mosq): Add API docs, memory consideration and tests

components/mosquitto/port/include/mosq_broker.h

@@ -8,9 +8,24 @@
 
 struct mosquitto__config;
 
+/**
+ * @brief Mosquitto configuration structure
+ *
+ * ESP port of mosquittto supports only the options in this configuration
+ * structure.
+ */
 struct mosq_broker_config {
-    char *host;
-    int port;
+    char *host; /*!< Address on which the broker is listening for connections */
+    int port;   /*!< Port number of the broker to listen to */
 };
 
-int run_broker(struct mosq_broker_config *config);
+/**
+ * @brief Start mosquitto broker
+ *
+ * This API runs the broker in the calling thread and blocks until
+ * the mosquitto exits.
+ *
+ * @param config Mosquitto configuration structure
+ * @return int Exit code (0 on success)
+ */
+int mosq_broker_start(struct mosq_broker_config *config);