Clearer error when xfel-calibrate would run no jobs

Description

If you get the input directory wrong for a notebook with concurrency options set, xfel-calibrate can fail with a cryptic error when it tries to submit the finalize job, because there are no jobs before it. This simply fails sooner with a clearer error in such cases.

How Has This Been Tested?

Running this interactively:

python -m xfel_calibrate.calibrate JUNGFRAU CORRECT \
    --slurm-partition exfel --karabo-id FXE_XAD_JF500K --karabo-da JNGFR03 \
    --roi-definitions 3 50 110 0 1023 -2 3 120 180 0 1023 -2 \
    --in-folder /gpfs/exfel/exp/FXE/202202/p003079/raw/r0192 --run 192 \
    --out-folder /gpfs/exfel/data/scratch/kluyvert/jf-corr-p3079-r192

Types of changes

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• My code follows the code style of this project.

Reviewers

@schmidtp