preprocess_obs: filter obs list for LAT formatted obs_ids

[davidvng]

Adds bool argument to preprocess_obs.py for LAT observations. Since LAT obs_ids are split by optics tubes with timestamps within about 10 seconds of each other, we only need to run preprocess_obs on one of them since it loads the entire aman with no signal. Without this, preprocess_obs runs redundant processes.

[msilvafe]

Ok but this approach I think begs the question how do you connect your single obsid which is for a single lat tube to all of the 7 obsids associated with this? I think you actually need to add some sort of database or link file that maps between your single obsid and the 7 associated ones.

[davidvng]

@msilvafe I added handling for obs grouping by adding the list of grouped obsids directly to the db. I tested this on the existing LAT planet obs so far and everything seems to work.