MQTT fixes and improvements via aws-crt update (#135)

Update brings:
- **IMPROVEMENT**: The MQTT `on_message` event, and the topic-specific callback passed to `subscribe()`, have added `dup`, `qos`, and `retain` params.
- **IMPROVEMENT**: Outgoing MQTT `Payload` type now accepts `ArrayBuffer` and any `ArrayBufferView` (ex: `Uint8Array`) type.
- **BUGFIX**: `on_message` payload typescript signature changed from `Buffer` to `ArrayBuffer`.
  - This is a semi-breaking change. There were two callback passing payloads, one signature claimed to pass `ArrayBuffer` payloads and the other claimed to pass `Buffer` payloads. In reality the node implementation always passed `ArrayBuffer` and the browser implementation always passed `Buffer`. Now, both callbacks share a signature, they both claim to pass `ArrayBuffer` and both the node and browser implementations **actually do** pass `ArrayBuffer`
- **BUGFIX**: browser MQTT `publish()` no longer tries to turn everything to strings. `ArrayBuffer` and `ArrayBufferView` types will pass their bytes straight through.
- **BUGFIX**: browser MQTT `unsubscribe()`

Author: graebm

package-lock.json

@@ -30,6 +30,6 @@
     "typescript": "^3.9.7"
   },
   "dependencies": {
-    "aws-crt": "1.3.8"
+    "aws-crt": "1.5.1"
   }
 }

package.json

@@ -147,9 +147,9 @@ async function execute_session(connection: mqtt.MqttClientConnection, argv: Args
         try {
             const decoder = new TextDecoder('utf8');
             if (argv.mode == 'both' || argv.mode == 'subscribe') {
-                const on_publish = (topic: string, payload: ArrayBuffer) => {
+                const on_publish = (topic: string, payload: ArrayBuffer, dup: boolean, qos: mqtt.QoS, retain: boolean) => {
                     const json = decoder.decode(payload);
-                    console.log(`Publish received on topic ${topic}`);
+                    console.log(`Publish received. topic:"${topic}" dup:${dup} qos:${qos} retain:${retain}`);
                     console.log(json);
                     const message = JSON.parse(json);
                     if (message.sequence == argv.max_pub_ops) {

samples/node/basic_discovery/index.ts

@@ -108,9 +108,9 @@ async function execute_session(connection: mqtt.MqttClientConnection, argv: Args
     return new Promise(async (resolve, reject) => {
         try {
             const decoder = new TextDecoder('utf8');
-            const on_publish = async (topic: string, payload: ArrayBuffer) => {
+            const on_publish = async (topic: string, payload: ArrayBuffer, dup: boolean, qos: mqtt.QoS, retain: boolean) => {
                 const json = decoder.decode(payload);
-                console.log(`Publish received on topic ${topic}`);
+                console.log(`Publish received. topic:"${topic}" dup:${dup} qos:${qos} retain:${retain}`);
                 console.log(json);
                 const message = JSON.parse(json);
                 if (message.sequence == argv.count) {