return only single beam

[lmorabit]

this uses information from the AveragingPipeline product to find the unique processIdentifier which then allows you to pull only the correlated data products you want, i.e. from the SAS id that is given.

Tested that it provides the right data products but note that what's printed from the print_observation_details prints out the original observation SAS ID, not the SAS ID that you search for.

[lmorabit]

also can line 130 be updated so the srm_*.txt file name is based on the sasid (which is what you searched for), not the target.observationId (which is the sas id of the original observation and is likely different)

[tikk3r]

I think it all looks good in principle. I just need to check if it still works correctly in combination with finding the corresponding calibrators. If I remember right, the start and end times of the AveragingPipeline products represent that of the pipeline and not the observation, meaning it would be looking for the wrong calibrators.