This metadata file subsumes the old retrieved constants YAML file.  The commit includes some refactoring centered around pathlib.

Fix/Unused Variables

Going through some of the warnings my IDE is throwing up so I'll probably end up doing a couple of these tiny pull requests.

- `cal_tools/cal_tools/agipdlib.py`: `corr_bools={}` setting keyword arguments to mutables isn't a great idea since the state can persist across function calls, maybe in this case that was the intention but it usually isn't. Changed it to `None` and then set it to a dict if no argument is given.
- `cal_tools/cal_tools/lpdlib.py`: `self.cnl = True` was set, but it looks like that should have taken its value from the `correct_non_linear` argument, set it to that.
- `cal_tools/cal_tools/metrology.py` an `offset` is defined but never applied to the coordinates. Similar code appears throughout the file so I just did the same thing there as well, think it should be correct.

See merge request detectors/pycalibration!415

[AGIPD][CORRECT] Apply pulse index selection/validation after common-mode correction

See merge request detectors/pycalibration!407

See merge request detectors/pycalibration!410

[DSSC][CORRECT][DARK] Feat/dss cconditions

See merge request detectors/pycalibration!374

Corrected pnCCD Main notebooks for path to slow data, etc.

See merge request detectors/pycalibration!371

Update to  cal_db_interactive version 1.6.4

Closes calibration_workshop#221

See merge request detectors/pycalibration!414

This version is actually set for the iCalibrtionDB package, so going forward, updating should be
more pleasant.

Add CI config

See merge request detectors/pycalibration!402

[AGIPD][CORRECT] FIX/Avoid applying ff_gain factor in SlopesFF is not retrieved

See merge request detectors/pycalibration!404

[AGIPD] [Correct Summary] Make use of karabo_id to only load data from that detector

Closes calibration_workshop#225

See merge request detectors/pycalibration!397

Fixes for bugs discovered during testing 3.0.0-beta on production

See merge request detectors/pycalibration!396

[AGIPD] Remove references to DETLAB mini-half

See merge request detectors/pycalibration!394

Closes calibration_workshop#226

See merge request detectors/pycalibration!398

Extend slopesFF with last usable cell

See merge request detectors/pycalibration!395

Fixes for testing 3.0.0-test03

See merge request detectors/pycalibration!392

Closes calibration_workshop#219

See merge request detectors/pycalibration!393

Fix/remove unused influx db

See merge request detectors/pycalibration!388

Fix/3.0.0 test02 fixes

See merge request detectors/pycalibration!391