Fix and improve TACA for handling QC runs

[kedhammar]

• Make sure TACA can handle runs that generate NO sequencing data at all
• Refactor logic of control function to reduce complexity
  • Introduce custom Exception for quiet skipping (waiting on) runs
• Improve documentation
• Minor polishing of test to pass

Tested in isolated environment on ngi-preproc for handling a bunch of QC runs.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 74.24242% with 17 lines in your changes are missing coverage. Please review.

Project coverage is 21.79%. Comparing base (802cc78) to head (91f86ce).

Files	Patch %	Lines
taca/illumina/Runs.py	0.00%	7 Missing :warning:
taca/analysis/analysis_nanopore.py	86.04%	6 Missing :warning:
taca/nanopore/ONT_run_classes.py	84.61%	2 Missing :warning:
taca/analysis/analysis.py	0.00%	1 Missing :warning:
taca/illumina/MiSeq_Runs.py	0.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #419 +/- ## ========================================== + Coverage 20.46% 21.79% +1.33% ========================================== Files 28 28 Lines 3914 3936 +22 ========================================== + Hits 801 858 +57 + Misses 3113 3078 -35 ```

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[kedhammar]

I'll revisit this to fix failing lints and coverage next week after deploying #418 and addressing any mergre conflicts.