Stop tts streaming, when bargeIn is enabled for gather verb and input is detected (#1154)

https://github.com/jambonz/jambonz-feature-server/issues/1153

lib/tasks/say.js

@@ -107,7 +107,7 @@ class TaskSay extends TtsTask {
       throw new SpeechCredentialError(
         `No text-to-speech service credentials for ${vendor} with labels: ${label} have been configured`);
     }
-
+    this.ep = ep;
     try {
 
       await this.setTtsStreamingChannelVars(vendor, language, voice, credentials, ep);
@@ -292,8 +292,10 @@ class TaskSay extends TtsTask {
       if (cs.isInConference) {
         const {memberId, confName} = cs;
         this.killPlayToConfMember(this.ep, memberId, confName);
-      }
-      else {
+      } else if (this.isStreamingTts) {
+        this.logger.debug('TaskSay:kill - clearing TTS stream for streaming audio');
+        cs.clearTtsStream();
+      } else {
         this.notifyStatus({event: 'kill-playback'});
         this.ep.api('uuid_break', this.ep.uuid);
       }