refactor answer code into one location

lib/session/inbound-call-session.js

@@ -43,20 +43,6 @@ class InboundCallSession extends CallSession {
     }
   }
 
-  /**
-   * Answer the call, if it has not already been answered.
-   */
-  async propagateAnswer() {
-    if (!this.dlg) {
-      assert(this.ep);
-      this.dlg = await this.srf.createUAS(this.req, this.res, {localSdp: this.ep.local.sdp});
-      this.wrapDialog(this.dlg);
-      this.dlg.on('destroy', this._callerHungup.bind(this));
-      this.emit('callStatusChange', {sipStatus: 200, callStatus: CallStatus.InProgress});
-      this.logger.debug(`CallSession:propagateAnswer - answered callSid ${this.callSid}`);
-    }
-  }
-
   /**
    * This is invoked when the caller hangs up, in order to calculate the call duration.
    */