Make thumbnail for lamella evaluation images

[tieneupin]

Another scoped PR to extend the lamella image registration workflow. Adds the logic needed to save a thumbnail image of the incoming lamella image to the path "{visit_dir}/processed/grid_{slot_number}/lamella_evaluation_images/lamella_{lamella_number}_{timestamp}_{step_name}.png".

The main run test for this workflow has also been overhauled so that it is run using the test database session we have set up, to verify that database inserts are correct. This will be heavily made use of as the workflow is further extended and more database inserts and calls are added.

Additionally, minor optimisations were made to the atlas registration workflow to improve readability and memory management when opening images.

[codecov]

Codecov Report

❌ Patch coverage is 82.60870% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 55.11%. Comparing base (d28bf70) to head (84e30bd).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #898      +/-   ##
==========================================
+ Coverage   55.08%   55.11%   +0.03%     
==========================================
  Files         103      103              
  Lines       11532    11550      +18     
  Branches     1530     1531       +1     
==========================================
+ Hits         6352     6366      +14     
- Misses       4838     4841       +3     
- Partials      342      343       +1     

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[stephen-riggs]

Looks fine. It relies heavily on the file naming being in the expected form, but I think that should be ok.