Stop the ASR pipeline if the task is deleted

[greenw0lf]

Currently, if a task is deleted and that task is the same as the current one being processed, the ASR pipeline will keep processing until it is finished or errors occur. Therefore, the pipeline should be interrupted whenever the API requests that the current task be deleted.

It is not trivial to implement. One way to do this is to use a global variable that is checked after every step of the ASR pipeline (or even during one of the steps, e.g. transcribing since it consumes the most time). Other options I looked at involved some threading, but the code examples there involve a loop in the method that is running on the thread, which is not applicable to our ASR pipeline.