Added new features to Speech Data Explorer
This pull request **introduces 2 alerts** when merging 918f97f81514c0f243321e81eb73adcd49c18cc3 into a711ca1ad2987797b1e80ac9b0ffd7479c0a4730 - [view on LGTM.com](https://lgtm.com/projects/g/NVIDIA/NeMo/rev/pr-a817d9e013ff7a00f492166aeb5bf1830ad2cba6)

**new alerts:**

* 2 for Except block handles &#39;BaseException&#39;
Added new features to Speech Data Explorer:
 - backend paging/sorting/filtering (allows to work with large datasets)
 - support for assigning a port
 - minor tweaks to UI

Signed-off-by: Vitaly Lavrukhin <vlavrukhin@nvidia.com>