Add session description and speaking listeners

src/client/voice/util/SecretKey.js

@@ -0,0 +1,10 @@
+class SecretKey {
+  constructor(key) {
+    this.key = new Uint8Array(new ArrayBuffer(key.length));
+    for (const index in key) {
+      this.key[index] = key[index];
+    }
+  }
+}
+
+module.exports = SecretKey;