Integrate atc-react with main atc project to make DN links in RAs working

[yugoslavskiy]

There are placeholders for Data Needed (DN) in RA's requirements field.
For now, it's not clear what is it. There is no link or explanation. So we need to:

1. Develop Data Needed categories (sometimes there are only categories, it need to be worked out)
2. Integrate them with atc-react, so the requirements will have links to the DN description
3. Develop a description of the relations

At the same time, there is ongoing activity on integration with OSSEM. We need to find a way to get all the stuff done in the most efficient way.