replace / add road_segment_id in NewsFlash (including history)

[atalyaalon]

We want to make sure we're using only road_segment_id in our DB, hence I suggest updating it (also historically) and either remove completely road_segment_name or keep it but make sure they both are updated together

API used by FE needs to be updated accordingly as well (in flask_app.py)

I tried to add it in this commit as a part of this pr but understood it requires more testing and hence needs to be in a separate issue and pr