feat: rest:dial amd (#339)

Add support for sending 'amd' property in createCall REST API and also added support for using any of the speech vendors for STT
---------

Co-authored-by: Dave Horton <daveh@beachdognet.com>

lib/session/rest-call-session.js

@@ -21,6 +21,10 @@ class RestCallSession extends CallSession {
     });
     this.req = req;
     this.ep = ep;
+    // keep restDialTask reference for closing AMD
+    if (tasks.length) {
+      this.restDialTask = tasks[0];
+    }
 
     this.on('callStatusChange', this._notifyCallStatusChange.bind(this));
     this._notifyCallStatusChange({
@@ -44,6 +48,10 @@ class RestCallSession extends CallSession {
    * This is invoked when the called party hangs up, in order to calculate the call duration.
    */
   _callerHungup() {
+    if (this.restDialTask) {
+      this.logger.info('RestCallSession: releasing AMD');
+      this.restDialTask.turnOffAmd();
+    }
     this.callInfo.callTerminationBy = 'caller';
     const duration = moment().diff(this.dlg.connectTime, 'seconds');
     this.emit('callStatusChange', {callStatus: CallStatus.Completed, duration});