Talknet bug fix & TalkNet Training tutorial 
* Add has_audio parameter to speech_collate 
    * @blisc I wouldn't like to write new `speech_collate` for TalkNet dataset, let's reuse old version with `has_audio` parameter?
* Log warning in `setup_optimizaton` when Trainer is not specified 
* Update TalkNet models that were without trainer in constructor
* TalkNet Training tutorial notebook
    * This version of notebook has 6 TODOs. It is related to branch name, link to new version of paper and pretrained models that are currently not in NGC (@stasbel, please, add them and we can finish it). Without fix, we **shouldn't** merge it. 

Signed-off-by: Oktai Tatanov <oktai.tatanov@gmail.com>