Add a NISAR topic

[jhkennedy]

Ideally, notifications for all NISAR products should be in one queue, with examples on how to filter by product type.

Need to gather all the NISAR collection short names; can use this list of concept IDs:
https://github.com/asfadmin/Discovery-asf_search/blob/master/asf_search/CMR/datasets.py#L20-L261

Note: it has concept IDs for Prod, UAT, and SIT, so it's expected some collections in that list won't be found in prod. We only care about Prod here.