Check Registry against refl/expt files

[ndevenish]

This was previously done implicitly, but only when dials_regression was present. This makes the test explicit, and works with dials-data (so that it will work on e.g. CI with restricted access to test cases).

[codecov]

Codecov Report

Merging #650 (7aba9d4) into main (436a1b6) will decrease coverage by 0.30%.
Report is 1 commits behind head on main.
The diff coverage is 18.13%.

❗ Current head 7aba9d4 differs from pull request most recent head e831497. Consider uploading reports for the commit e831497 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #650      +/-   ##
==========================================
- Coverage   39.40%   39.11%   -0.30%     
==========================================
  Files         178      179       +1     
  Lines       15542    15757     +215     
  Branches     3004     3040      +36     
==========================================
+ Hits         6125     6164      +39     
- Misses       8836     9010     +174     
- Partials      581      583       +2