.ctm in data simulator annotator compliant with RT-09 specification
Sign-off issue. Will re-open another PR. Closing.
An attempt to fix https://github.com/NVIDIA/NeMo/issues/7445 so that the data simulator .ctm are compliant with RT-09 specification (see https://web.archive.org/web/20170119114252/http://www.itl.nist.gov/iad/mig/tests/rt/2009/docs/rt09-meeting-eval-plan-v2.pdf): 
```
<SOURCE><SP><CHANNEL><SP> <BEG-TIME><SP><DURATION><SP><TOKEN><SP>
<CONF><SP><TYPE><SP><SPEAKER><NEWLINE>
```

I have put <NA> for fields unknown e.g. <TOKEN>. 
This makes it also easy to use the generated sessions with https://github.com/lhotse-speech/lhotse