(DSSC CORRECTION) Feat/Message for missing devices without NB failure

In proposal 900095 and run 1520 only the raw file of Q4M4 was available.

Two problems occurred:

1. No message for indicating that modules or files are missing.
2. Notebook failed at the plotting part because 16 images were plotted using a hard coded first_idx value greater than number of corrected data.

In this MR:

• Proper message for indicating missing module files.
• actual first_idx is used and 1st 128 images are plotted to be similar to the description in the notebook and report.
• refactoring code to avoid saving missing or skipped modules as they are not used anywhere.

@karnem @samartse