Add a test for get_pdu and initialize_from_db

See merge request detectors/pycalibration!459

Add AGIPD Fixed Gain Mode

See merge request detectors/pycalibration!438

Add AGIPD Fixed Gain Correction

See merge request detectors/pycalibration!451

Add instructions on setting up GitLab SSH to README

See merge request detectors/pycalibration!455

Fix SQL parameter for query-rid action

See merge request detectors/pycalibration!460

It needs to be a tuple even when there's a single argument.

https://in.xfel.eu/redmine/issues/87389

We had both imported cal_tools.cython.agipdalgs as calgs
# Conflicts:
#   cal_tools/cal_tools/agipdlib.py

[AGIPD][CORRECT] Fix/Add missing imports for agipdlib

See merge request detectors/pycalibration!454

Merge branch 'feat/agipd-fixed-gain-correction' of ssh://git.xfel.eu:10022/detectors/pycalibration into feat/agipd-fixed-gain-correction

Merge branch 'feat/agipd-fixed-gain-correction' of ssh://git.xfel.eu:10022/detectors/pycalibration into feat/agipd-fixed-gain-correction

- trailing whitespace
- unused variables
- unused imports
- misc formatting

nbstripout, some flake8 (removing unused variables, imports), isort, simplifying retrieve_constants
as it does not need to work under ipyparallel

Merge branch 'feat/agipd-add-fixed-gain' of ssh://git.xfel.eu:10022/detectors/pycalibration into feat/agipd-add-fixed-gain

Currently, there is no way to specify most parameters when requesting darks via MyMDC - values are
just loaded from the calibration configurations repository.  To allow for using different offset
thresholds in fixed gain mode versus adaptive gain mode, adding these extra parameters is a
pragmatic if not elegant solution for now.